DirectMaterial.com Blog

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  • What is Lead-Free Brass? Why Buy It?

    In November, DuraChoice Co. will unveil a new line of lead-free brass ball valves. I thought this would be a good time to go over what exactly “lead-free” means and why it’s important to have a lead-free brass option.

    Locking Handle Lead-Free Ball Valve DuraChoice begins shipping its new lead-free brass ball valves in November. The full port valves come in sizes 1/4" to 2".

    Over the past few years, federal and state governments have enacted laws to limit people’s exposure to chemicals in potable water. The most sweeping of these laws was an amendment to the federal Safe Drinking Water Act, redefining “lead-free” as a maximum weighted lead content of 0.25% on the wetted surface of plumbing products. Before that 2011 amendment, the legal limit was 8%.

    Section 1417 of the act makes it illegal to “introduce into commerce any pipe, or any pipe or plumbing fitting or fixture that is not lead free, except for a pipe that is used in manufacturing or industrial processing.” In other words, leaded pipes, fittings and valves can only be used in processes that don’t involve contact with food, drink or any other form of bodily intake.

    The federal legislation went into effect Jan. 4, 2014. In addition, many states have introduced lead-free laws, including California, Maryland, Vermont and Louisiana.

    Although the legislation does not specifically target them, the new regulations have the most dramatic impact on brass and bronze pipes, fittings and fixtures which deliver potable (read “drinkable”) water.  That is because lead has long been used in the foundry process to make brass castings pressure tight.

    Lead is sometimes added in concentrations of about 2%. Because lead is the last element in brass to solidify, it would seep into the smallest holes left in the brass, causing the material to stiffen it up better. Most of the lead winds up on the surface and can be smeared during the machining process.

    If that happens, the amount of exposed lead and the potential for lead leaching increases greatly, even in brass parts of relatively low lead content.

    Lead-free brass replaces the lead with silicon, bismuth or mixed copper alloys, which help address those issues. DuraChoice’s lead-free ball valves use silicon brass C87600, which gives them good machinability and pressure tightness.

    As far as appearance goes, there is no appreciable difference between the lead-free brass and other brass parts. It should also be understood that all brass “lead-free” parts may still contain trace amounts of lead, but no more than the 0.25% mandated by the law, so the parts should be labeled clearly to avoid confusion.

    The new DuraChoice lead-free brass valves (VBB02/VBB02LH) have an "LF" marking on the body and come with a plastic tag to identify them as lead free. Certified under UL, CSA, FM and UPC regulations, the valves also bear those certification marks. Their full port design allows for unimpeded flow and less risk of cavitation.

    The valves come in both locking and non-locking handle varieties in sizes 1/4” to 2”. They are available at DirectMaterial.com and other online distributors.

  • What kind of industrial valve are you?

  • Measuring a Strainer Screen: Microns vs. Mesh?

    Microsoft Word - Mesh.docWhen we are talking about strainers and filters, we are usually talking in terms of microns or mesh. But what do those terms mean?

    Well, they actually mean the same thing, but are expressed in opposing orders. In a strainer or filter, they measure the size of the openings that materials pass through and consequently what is stopped.

    A micron, short for “micrometer”, is a millionth of a meter in size. That works out to about .00004 inches.

    So, calling it “tiny” would be an understatement, but tiny things add up. Bacteria can be as small as 0.2 microns or as big as 20 microns, although they are usually on the smaller size. A human red blood cell ranges between 8-12 microns. White blood cells are larger at about 25 microns. A human hair is 75 microns in diameter, although that varies depending on the person. And on it goes.

    Beach sand is about 100 microns, the smallest size screen that DirectMaterial.com keeps in stock for our y-strainer. We also stock 20 mesh (840 micron-wide openings), by-the-by.

    Mesh is a bit more straightforward compared to microns. Take one square inch of filtering material (screen) and count the holes in it. If you have 80 openings in that area, then you have an 80-mesh screen. If you have 200, then it is 200-mesh and so forth.

    Therefore, the bigger the mesh “size”, the more the smaller the particles filtered. That means the two measures run in reverse order, so a #10 mesh has openings of 2,000 microns and a #400 mesh has openings of about 37 microns wide.

    It’s also worth noting that #400 mesh is about the largest (or smallest, depending on your perspective) that mesh size is generally used. Screens finer than that are usually expressed in microns because the holes are so small that “mesh” becomes imprecise, since different gauges of wire are used to make the screen.

    Everything as clear as mud? Wonder what size of screen you should use to filter mud? Take a look at the chart to the right. It breaks everything down in mesh, microns, millimeters and inches.

  • What is a pressure snubber?

    Getting snubbed doesn’t have to be a bad thing. In fact, something called a “snubber” may be just what you need if you are measuring pressure in a system where pressure spikes and pulsation are a concern.

    In the past week, two customers have called asking for a solution to processes damaging their gauges. One had a gauge connected to a line downstream from a quick open/shutoff valve. When the quick opening valve was activated, the rapid change in pressure caused an internal seal of their pressure gauge to rupture, allowing water into the gauge casing.

    Snubber valve intake An up close view of the porous disc type of snubber shows the sintered disc that filters and slows fluids and gasses.

    The gauge was rated for the nominal pressure the customer was measuring, but the pressure spike pushed past that pressure range just enough to break the gauge and make it unreadable. It happened to two makes of the gauge from separate vendors, so the customer knew it wasn’t faulty manufacturing.

    We recommended the customer look into a snubber, a specialty part with a few different design types which work to arrest rapid pressure fluctuation and spikes by slowing the maximum speed a substance can travel. Snubbers also make gauges measuring quickly oscillating media more readable and less likely to suffer damage.

    Those familiar with plumbing might equate them to water hammer arrestors installed in homes to lengthen the life of the pipes.

    On the low-cost end of the snubber spectrum is the porous disc type (also known as a “filter type”). The fixed disc creates a semi-permeable barrier between the incoming pressure and the pressure gauge’s orifice. The pressure meets that disc and has its force distributed through the metal mesh, slowing it so that it will not harm the gauge. The pressure rises gradually, so that the gauge doesn’t jump a gear or burst a bourdon tube.

    The porous disc design allows consistent pressure at low speeds, though, so that the gauge’s readings are not affected by the filtering material.

    The downside of a porous disc snubber is that it can become clogged, depending on the process being measured. In that case, the readings would be affected and the snubber would have to be cleaned by flushing it from the gauge side with a solvent.

    A piston-type snubber has a little more advanced design that is often self-cleaning. Often designed in two pieces, the piston inside the snubber moves freely, acting as a barrier to the rapid increase in pressure. When pressure increases too rapidly, the piston is forced against the orifice leading to the gauge, stemming the flow for milliseconds. As long as it is just a spike, that should be long enough to avoid damage to the gauge.

    This type of snubber can usually be “tuned” to meet a process’s needs by using easily changed pistons of varying sizes. The diameter of the piston and its clearance within the snubber determine the rate of “dampening” that occurs.

    A third “adjustable” snubber takes that fine tuning to another level. Many use a combination of a ball check to block surges and a kind of choke valve to smooth out the flow of material into the gauge. The ball check acts a lot like the piston-type snubber in that it is a passive element until a rapid change in pressure pushes it into action.

    Even adjustable snubbers without the ball check can be effective in smoothing out a lot of pulsation, thanks to the integrated choke valve, which will only allow so much fluid through at one time. In a pinch, a regular needle valve could be substituted, but that is not necessarily a permanent solution to the above customer’s problem. In that case, it was a major momentary spike in pressure that damaged the gauge and a needle valve alone wouldn’t have completely arrested the surge.

    Many adjustable snubbers also have the benefit of leak-tight shutoff, allowing the operator to remove the gauge for repair or removal.

    Pressure ratings for snubbers can range from 1,000-20,000 psi, depending on type, size and the material used. Be sure to consider how much pressure might be introduced through spikes, water hammers and pulsation, as well as the media being measured, when deciding on the right snubber.

    Finding the right one can improve gauge readability and protect the gauge from serious damage.

  • Fittings: What is an Elbow?

    If all you know about elbows is that you aren’t supposed to eat with them on the table, you are about to learn a few things.

    Different kinds of elbow fittings In addition to the flex point for your arm, elbows are industrial fittings that change the direction of piping. The connections allow you to reroute regularly threaded pipes to turn corners or fit in limited space without the expense of buying a pipe bender.

    Standard elbows come in a few different angles – 45°, 90°, and, although they are less common, 22.5° angles – and can be made of the same materials as any other piping. DirectMaterial.com has a wide selection of elbows and other fittings in Stainless Steel 304 or SS316.

    Although the names are mostly self-explanatory, there are a few variations in the elbows that are worth exploring.

    The 90° elbow is also called a “90° ell” (pronounced like the letter “L”) or sometimes a “quarter bend” because the right angle at which flow is redirected is one quarter of 360°.

    The 90° elbow is used in spaces that require a major turn. Although this may be a necessity, the flow rate and pressure within the pipe is affected. Just as with any piping system, the material under pressure hits the elbow and would like to continue in the same direction. When it meets the resistance of the elbow wall, it is forced to change direction (deflected) at a cost to the pressure.

    The internal length of the elbow plays a part in that resistance. A quarter bend elbow made to fit in a tight space will create more pressure loss because the material being transported has to make the change more rapidly.

    A look at the difference between long and short radius elbowsElbows with a center-to-face dimension of 1X the pipe size are called “short radius” bends and force a quick turn. They have greater pressure loss than “long radius” bends which have a center-to-face length of 1.5X the pipe size. The distance traveled within the fitting is farther, creating a smoother transition for the material, which also means less turbulence in the system.

    Long radius bends are used when flow rates are more important than space preservation in the plumbing system design. Both 45° and 22.5° ells tend to be long radius, which means they have less pressure loss than 90° ells.

    Elbows come in a variety of connections, including threaded, weldable, socketed and flanged. When it comes to threaded elbows, male-x-male and female-x-female connections are most common. “Street elbows”, however, come in male-x-female configurations.

    Elbows normally have the same size connection on both ends. When one is smaller than the other, that fitting is called a “reducing elbow”. These should be used with caution, as the change in pipe diameter will result in a change in pressure.

    All of these factors should be considered when looking for the right elbow for your project. Otherwise you might end up with the “left” one.

    Ahhh, word play is fun.

  • Fittings: What is a Pipe Nipple?

    Today, we are going to talk about short lengths of pipe threaded to attach fittings at both ends. Ready? “Nipple.”

    There, I said it. Get your giggles out of the way. The fourth grader in all of us loves a word that sounds like it could be dirty, but isn’t.

    Nipple.

    Leaving aside that many people aren’t immature as I am, using the word “nipple” to describe a short piece of pipe is surprising to people who don’t deal regularly in plumbing supplies. And it isn’t entirely clear where and when people started using the term “nipple” to refer to pipes.

    I couldn’t find the first use of first use of pipe nipple in plumbing or engineering. The best I could do was find the etymology of the word from www.etymonline.com. It dates from at least the 1530s and comes from a root meaning "bill, beak, snout" - literally “small projection.”

    Pipe nipples come in a lot of shapes and sizes.But no matter what the basis for the word, it is now in common use in plumbing. And what’s more, there are several different types/subsets of pipe nipples to contend with. A short list includes: close nipple, hexagonal nipple, long hex nipple, reducing nipple, hose nipple and welding nipple. I’m sure there are more, but we’ll stick with those for now.

    In its most basic form, a nipple is a short length of pipe with male pipe threads at both ends for connecting other fittings. You may also see them referred to as “barrel nipples”. Generally speaking, there is a short distance of unthreaded pipe between the two threaded ends, depending on how far apart you need the attached fittings to be.

    When there is no bare pipe (read “unthreaded”) between the two connecting ends, the part may be called a “close nipple” or a “running nipple”. In that case, connected fittings come close to touching one another and very little of the nipple can be seen.

    Although some constructions require such tight placement, close nipples can be difficult to work with, since unscrewing them requires holding tight to part of the threaded area. That can damage the threads. Plumbers who need to use them often invest in an internal pipe wrench (also known as a “nipple wrench”), which expands inside the pipe to hold it in place without damaging the threads.

    In cases where you can spare a little space between threaded ends, you can use a “hexagonal nipple”, which has a hexagonal section in the middle. It functions like a nut that can be gripped by a normal wrench, providing a greater mechanical advantage than normal rounded pipe. A hexagonal nipple with more distance between the threaded ends is called, no surprise, a “long hex nipple”.

    For projects which require a change in pipe dimension, you can buy a “reducing nipple.” Sometimes called an “unequal nipple”, it takes a female fitting with a larger connection and attaches it to a smaller one. Care should be taken when using these parts since a reduction in pipe diameter can mean more pressure and greater flow rate in the smaller pipe/fitting. The nipple usually has a hexagonal center, although not always.

    There is a specialty nipple called a “hose nipple” for processes which require connection to tubing. That fitting features a male threaded connection on one end and a hose barb on the other. The hose barb may be the same size as the pipe connection or it may be reduced.

    The final variant we will talk about is the “welding nipple,” which has a threaded connection on one end and normal cut pipe at the other. As the name implies, this part is designed to be welded to piping, a fitting or a tank. The unthreaded end of the pipe provides more surface area for the use of solder or other welding materials to make the connection stronger. The benefit of the welding nipple is that once the unthreaded end is connected, you can connect pipes or other fittings to the threaded end much more easily.

  • What style of pressure gauge connection works best?

    Different kinds of pressure gauge connection

  • Choosing the Right Valve: Flow Rate, Etc.

    So, we’ve settled on the kind of valve and the material it is going to be made out of. Now for some of the other considerations you might want to … well, consider.

    Question 3: What else do you need to know about valve materials?

    The last article was getting a little long, so I thought I would save the discussion of valve seals and seats for this article. This is not going to be as exhaustive as the previous article, but these materials can be an important factor in your decision. They can have just as much of an effect on the valve’s properties.

    Although some valves come with metal seats/seals, the vast majority of valve seats and seals are going to be made of plastics. We discussed a few of those in the previous article, but the list of possible seal materials is as endless as the chemical combinations that can be dreamed up by really smart people in white coats. Since we are talking about synthetic materials, there is always a new material in the works and you should do research into the specific properties (and any legal/health regulations) of any valve seal material before using it.

    However, to give you some idea of the variety out there, we’ll talk about a few.

    DELRIN® is capable of withstanding pressures up to 6,000 psi and nuclear radiation up to 106 rads. But it should not be used with oxygen service or steam. The temperature range for the valve is -70° to 180°F.

    PEEK® (polyether ether ketone) on the other hand can work up to 480°F and can withstand pressures up to 4,500 psi – although not at the same time. PEEK has excellent chemical and abrasion resistance.

    PTFE (polytetrafluoroethylene), commonly known as “Teflon”, is the most common seal material. It has a temperature range of -50° to -320°F and works well up to 1,000 psi.

    A close cousin to PTFE is Reinforced PTFE (RPTFE), which uses a glass filler to improve the polymer’s life cycle and temperature rating.

    Question 4: What size and thread style do you need?

    When you buy a pair of pants at the store, you can use a tape measure to check your waist size and inseam, then make your choice. Measuring a valve connection isn’t quite as simple.

    As covered in much greater depth in this article, if you don’t know the connection size, you need to measure the outside diameter (for male connections) or the inside diameter (female connections), then check it against a chart that list the correct size. That goes for both NPT (National Pipe Thread - Tapered; America’s standard thread type) and BSPT (British Standard Pipe - Tapered; the international standard).

    There are other thread types, including NPSC, NPTR, NPSM, NPSL and BSPP, which rarely show their heads in United States plumbing uses. NPT is the most common thread type for industrial plumbing use in the United States and the threading we sell in the United States. The threads are tapered to interlock better, helping prevent leaks with the assistance of pipe tape or pipe dope. NPTF (National Pipe Thread - Tapered for Fuel; sometimes called DrySeal) is very similar to NPT threading with the additional benefit of a better seal in fuel operations without the use of sealant.

    So, if NPT is pretty much the “end all, be all” in the U.S., why ask this question at all? Well, because if you don’t, you are opening yourself up to buying the wrong connection type, which will cause leaks and cost money.

    If you are adding this valve to an existing system, you have to be sure you are getting the right thread type, just in case. If you are building a new system, you want to make sure you have all the right parts before you begin.

    Question 5: Full port, standard port or reduced port?

    This is another question that you might not have a lot of input into, but bears consideration in certain circumstances. Like thread size, the flow restrictions of many valves will be pre-determined by their function. That is especially true of control valves, which limit flow by design.

    And although you may have the full, standard and reduced port options on other valve types, the most common place you will run into this is in ball valves. Since there aren’t really any twists and turns in most ball valve designs, ball valves have the potential for unobstructed flow.

    That is only true with full port valves, however. That’s what full port – sometimes called “full bore” - means. The opening in a full port ball valve’s center is the same, or very nearly the same, as the pipe connection size. A good rule of thumb is that full port valves are a minimum of 90% full size.

    You can compare that with standard port size – also known as “standard bore” - which reduces the center ball size by about one NPT pipe size. An informal survey of the industry shows that standard port valves are usually 75%-90% of full size.

    Some manufacturers offer valves with an even smaller bore size, usually listed as “reduced port”. These valves can be less than 75% of full size and are used mostly as backups or secondary valves. They can serve well in those roles, but in instances like the ones outlined below, you really need to go with a full port valve.

    Full port valves are usually more expensive than standard and reduced port valves, but they offer better flow rates and less potential for prohibitive chemical buildup along internal edges. Full port valves also minimize the chance for cavitation. Cavitation happens when tiny bubbles, or “cavities,” form in the process material and then implode from the pressure inside the valve. That implosion causes a shockwave which can be noisy and cause major damage to the valve over time.

    The bubbles are produced as a result of going from a higher speed flow area (such as the narrower area of a standard port valve) into an area of slower flow (when the valve opens back into the regular pipe size). Because full port valves do not have that internal change in flow rate, are less likely to cause cavitation.

    However, in most applications where full flow is not a major concern, standard port valves work just as well. It depends on the material being transported and the flow rate. Dense, pure liquids with high surface tension and transported at higher speeds are more likely to produce cavitation. They would benefit from full flow, whereas less viscous liquids moving at a slower rate would be fine in a standard port or reduced port valve.

    In that case, you could realize some cost savings and, depending on the design, save some space as well. The DuraChoice standard port valves sold on DirectMaterial.com as significantly smaller than the full port variety, making them easier to fit into some projects.

    You can learn more about the difference in full and standard port valves in this article.

    Conclusion

    Well, I hope these past few articles have given you a little bit to think about when it comes to valve choice. You will probably have a lot more project-specific questions as you move forward, but these questions should get you started down the right path. Be sure to search the DirectMaterial.com knowledge base if you have any other questions or write us at service@directmaterial.com if we can be of help.

  • Choosing the right valve: material

    OK, so you’ve settled on the kind of valve you need, but that’s not the material question, is it?

    Question No. 2: What should the ball valve be made of?

    At first blush, this may not seem like an important question. A valve’s a valve, so long as it does what it’s supposed to, right?

    Well, maybe. Or maybe, if you are a food processor, you slowly give your customers lead poisoning. I mean, who’s going to buy your burritos if all your customers are dead?

    Which material to buy your valve in Brass or Stainless Steel? These are just two of the choices available to you when choosing valves.

    That is, of course, a wild exaggeration, but lead leakage from brass valves make them less desirable in some industries than others. And while plastic valves can be a good choice in many situation, their lower burst pressures can rule them out of some uses.

    As with the previous discussion, we will be talking about a few major categories of materials. Although valves can be made out of pretty much anything, this should give you a good starting point, from which you can go on to do some serious research, including industry regulations (e.g. fire ratings and specific bans, such as the need for lead-free products), pressure ratings and media compatibility regarding which valve material works best with which media. We will post a compatibility chart soon for you to see.

    PVC and other plastics

    Plastics don’t corrode like metal valves, making them a leading material in some industries. Although there is a wide variety of plastics available, the most commonly used is polyvinyl chloride (PVC), which is resistant to water and chemicals, including acids.

    Because the valves do not rust, they don’t jam as easily, freezing the valve open or closed. Likewise, the valves are less likely to acquire as much buildup as metal valves, meaning less blockage of pipes and better flow rates for a longer period. This makes them good for industries where other piping and valves would need to be replaced regularly – although, as we will see later, other materials have strong corrosion resistance and other benefits.

    Plastic valves tend to be easier to install than metal valves, at least when it comes to physical labor. Plastic valves can be installed with hand tightening, plus a quarter-turn with a strap wrench. Compare that with the way metal valves are secured – that is, with as much force as you and your three best workers can muster.

    In fact, tightening the valves/piping too much can be a concern. Some experts say that plastic valve failures can be traced back to overzealous installers who put too much stress on the part when installing it.

    Another prime advantage of plastic valves is cost. Usually less expensive than brass or steel, plastic valves are also somewhat lighter than metal valves. That makes them cheaper to transport, adding to the savings.

    Where metal valves have an advantage over plastic ones is temperature and pressure. As temperatures rise, pressure ratings fall. That is true with all piping and valves. Plastic valves can serve admirably in many situations, but high temperature and high pressure applications often require a different material. PVC Grade 1 Type 1 has a pressure rating of about 150 psi at 75°. The maximum safe temperature for PVC is around 140°, at which point the pressure rating drops to just more than 30 psi. That is, of course, dependent on the chemicals being pumped through. Different media would affect the piping/valves differently.

    Valves made from other plastics, such as Kynar and Teflon (PTFE), have higher pressure and temperature ratings. Kynar valves are rated up to 230 psi and Teflon valves can withstand temperatures up to 300°. Other plastics work under extremely heavy pressure, but you will pay just as heavily for the material.

    And if you are paying more, then you might want to move up the materials chain to check out brass valves.

    Brass and Bronze Valves

    Brass and bronze are both copper alloys, which makes them stronger than plastics, generally speaking, with a mid-range price. They are the next step up in terms of pressure and temperature ratings, although they are not the top end.

    Brass is primarily a mixture of copper and zinc, although other metals may be added to give it different properties, including corrosion resistance (more on that later). Brass is considered one of the softer metals used for industrial valves, but the valves are rated higher than most plastics. You may find special cases where brass valves are rated higher, but most top out at around 600 psi.

    A mixture of copper and tin, bronze is a harder and more brittle metal than brass. It has similar pressure ratings to its brass counterparts.

    Brass and bronze both show high resistance to corrosion, with bronze performing especially strong against saltwater corrosion. Brass can go through a process called dezincification, in which the zinc in the part seeps out over time, leaving the copper superstructure which can become brittle and cause failure. Brass is more susceptible to that process in certain areas of the country, including areas of Texas, the Carolinas and Missouri. That said, brass usually has a comparable service life to bronze in most cases.

    Brass and bronze both respond better to higher temperatures than plastics because of their ability to absorb more heat. Both are good conductors, which makes them more efficient in plumbing systems. Brass piping and fittings are often prized in home plumbing because of the way the material balances malleability and high temperatures.

    Because of their chemical make up, both types of valves also accept solder and welding better than some other metals like stainless steel, which often must be abraded before welding to break down the oxide layer on its surface.

    Unfortunately, for all of the good things that brass valves have going for them, there is a drawback. Lead is often added in low levels to harden the alloys and assist in their machinability. Although the addition of lead is minimal – often less than 2% - and the likelihood of contracting lead poisoning extremely rare, the use of brass valves, fitting and piping can be a concern for people who manufacture foods and drinks.

    In some cases, lead can leak into the materials being transported. Therefore, the Food and Drug Administration (FDA) does not approve of brass valves being used. California has gone so far as to eliminate brass materials with lead content higher than 0.25% when they come into contact with a wetted surface.

    Lead-free brass is a substitute, where silicone is used instead of lead. DirectMaterial.com manufacturing partner, DuraChoice, recently introduced a new line of lead-free brass valves, which are UL and CSA certified. Because of the different manufacturing process, those parts are more expensive than normal brass valves.

    And if you are going to pay more, you might want to consider the next level of valve material – steel and stainless steel.

    Carbon Steel and Stainless Steel

    Steel is a very hard metal, which contributes to its resilience. The valves are not going to take damage like brass will, meaning they should resist leaks better over time.

    Likewise, they have a wider working temperature range, giving them more versatility. Add that to a longer life cycle and, even though they cost more than brass, you could save more over time.

    Like virtually every other part of this article, though, let me say “steel” has too many types to make a lot of blanket statements about it. However, we can talk about a couple of popular types – carbon and stainless steel.

    Carbon steel (also known as “mild steel”) is a mix of iron and carbon, although some other alloying elements may be used to harden the steel and give it greater corrosion resistance. And that is the main difference between carbon and stainless steel.

    We can talk about various hardness levels and ferromagnetism, but without special treatment, carbon steel is more likely to rust than stainless steel and that can mean a shorter service life.

    That is not to say those valves are not useful. Carbon steel valves can be used in many instances where pressure and temperature extremes make other materials unusable. DirectMaterial.com sells carbon steel valves pressure rated up to 6,000 psi and has added corrosion resistance thanks to its material make up.

    If you are looking for the top of the line in pressure ratings, high temperature functionality and corrosion resistance, though, you probably want to go with stainless steel. Stainless steels are iron alloys with chromium and nickel. Their chemical make up makes them highly corrosion resistant and particularly strong. The 6,000 psi valves mentioned above also come in Stainless Steel 316. Here’s an article about both types of high pressure valve.

    What’s with the “316” you ask? That is the type of stainless steel. It is extremely corrosion resistant thanks to higher levels of nickel and the addition of molybdenum. The three metals work in concert to make the valves much more resistant to chlorides. Stainless steel 316 is often used in fast moving marine environments, as well as food production. In fact, Stainless Steel 316, 304 and 302 are all FDA approved for food and beverage handling.

    Here is an article about the differences between SS316 and SS304, two of the more popular types of stainless steel for valve manufacturing.

    Summary

    To sum up, you should look at considerations like industry and environment as well as price when picking the right valve for your project. Take a look at the bottom line, but consider the factors that could affect it.

    You don’t want to pay more than you have to, but if you invest in pipes that you will constantly need to replace, necessitating downtime, that is going to hurt you in the long run. The same goes for buying products that could hurt production or your customers. Look at the different kinds of material on this list to narrow your search, then seek out a little more information on a specific material if it looks like it fits your needs.

    Next up, we’ll talk about sizing, flow rate and other considerations.

  • Choosing the right valve: Type

    OK. You know you need a valve to complete your project, but if you aren’t a professional plumber or engineer, you might not be sure which will work the best. Don’t worry, we’re here to help you find the right valve.

    Just answer the questions in the next few blog posts and you’ll be a lot closer to your decision. We are going to talk about valve purpose, material, pressure and sizing, as well as a few other things that will help make the decision easier.

    Unfortunately, the world of valves is wide ranging, with more specialty valves than you can shake a stick at. Rather than an exhaustive list of every valve variation, we will focus on some the major valve groups and try to get you thinking about the right questions to ask when deciding on the right part.

    Which gauge to useQuestion No. 1: What do you need your valve to do?

    Valves have two main functions: regulation and shut off. Determining that aspect of your project can often be the most important part of the decision.

    Shut Off Valves

    Shut off valves come in plenty of shapes and sizes, but they do what their name implies by completely closing down the flow of liquids or gasses. If your project requires only an on/off capability, a shut off valve is the simplest way to go.

    The most common type is a ball valve, which relies on the turning of a lever handle to engage the on/off mechanism, a solid metal ball with a pipe-sized opening drilled through the middle. When the opening aligns with the pipe, flow is possible. When the opening is perpendicular with the pipe, flow is not. Opening the valve partially is not recommended, as that can create cavitation and vibration, causing wear on the valve.

    A three-way ball valve is a specialty version of that valve. Sometimes called a “mixing valve,” it allows for both full shut off, redirection of flow from multiple sources and can, in some instances, be used to mix two sources together. We have a full article on the three-way ball valve here. Other variations include mini ball valves (which we will talk about later) and varying port/bore sizes.

    A second type of shutoff valve is the gate valve. Although sometimes used as a regulating valve, gate valves often use a hand wheel to make the shut off easier. By using a hand wheel on a spiraling track, you gain a mechanical advantage that the lever of a ball valve doesn’t offer. Turning the wheel drives the valve’s stem up or down, bringing the “gate” with it.

    That means that much less pressure must be exerted on the valve to make the valve close and that it can be closed incrementally, easing stress on the pipes and avoiding damaging “water hammer.” That incremental shut off gives rise to people using the valve as a regulator, although most engineers advise against this use, as it can cause greater wear and may cause leaks over time.

    With the exception of a lever-type “quick shut off” gate valve, gate valves take longer to close than ball valves, which usually only require a 1/4 turn.

    One thing to consider when deciding on whether to use a gate or ball valve is “clearance” for the valve to be manipulated. In close quarters, a gate valve might be the best option, because you do not need as much space to turn the wheel as you do to switch a lever.

    If quick shut off capability is necessary, a ball valve might be the right choice. Mini ball valves are good for smaller areas, because their levers do not extend beyond the valve body. But as the name implies, mini ball valves aren’t always large enough to get the job done. It is unusual to find mini ball valves larger than 1” NPT.

    Control valves

    Control valves, sometimes known as “regulating valves,” allow the user to select the amount and/or the direction of flow through a plumbing system, either manually or automatically, in the case of check valves.

    Control valves come in a variety of designs. Some of the most common manual control valves include globe valves and needle valves. Although the specifics of the design differ, these two types of valves share a zig-zag or “S” shaped channel in the valve. A stem, usually coming down vertically, introduces a stopper into the channel to completely close off the valve. When that stopper (or “needle” in the case of a needle valve) is raised, it allows fluid or gas to flow freely the opening and around the stopper itself.

    As the stopper is moved farther from the valve seat, the greater the flow. Because the design distributes the flow evenly around the stopper, there is less wear on any particular part. That means these control valves tend to have a longer life than gate valves pressed into service for the same regulatory job.

    Needle valves are often used with pressure gauges where high pressure may be present, but flow rate tends to be lower. Globe valves come in much larger sizes and are used to regulate all kinds of material. You can read more about global valves here or needle valves here.

    “Check valves” are a different type of control valve. They regulate the direction that liquids and gasses flow rather than the flow rate. As we will see, it takes a certain amount of pressure to activate the check valve, making them a kind of automatic control valve.

    Like many of the other valves in this article, a number of designs fall into the check valve category. However, we will be discussing two of the most common types, the swing check valve and the spring-assisted check valve.

    The swing check valve (full article here) relies on a swinging flap, hung vertically inside the pipe and held in place by gravity. When enough pressure is applied in one direction, the flap swings open, allowing flow to pass. Once that pressure decreases, the flap falls back into place. If pressure is applied from the other direction, the flap is pressed firmly against the valve seat stopping backflow.

    Because of the design, the swing check valve can only be installed horizontally. A spring-assisted check valve can be installed horizontally or vertically.

    Available in both “in-line” and “Y-Check” varieties (more info here), the major benefit of a spring check valve is its quiet and smooth operation. The valve uses a spring loaded stopper pressed against a valve seat. When enough pressure is applied against it, the spring contracts, allowing some fluids or gas to pass.

    The valve opens only enough to permit the flow needed and then closes swiftly, but because it is responding to the amount of pressure in the pipe, you do not usually have a “water hammer” effect.

    The swing check valve sold by DirectMaterial.com only requires 0.5 psi to open, while the spring-assisted check valve requires more pressure to be activated - as little as 1 psi or as much as 200 psi.

    Summary

    So, when deciding on a valve, take its operation into account. If you need some flow, especially if it should only ever travel in one direction, then a control valve is the way to go. If your only need is to stem the flow entirely – especially if it needs to be shut down quickly – then a shut off valve is probably the answer.

    Next week, we’ll talk about the materials used in valves and their different properties.

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