Tag: regulator

Understanding Pressure Requirements For Your Compressed Air System

Published on by Russ BowmanLeave a comment

One of the advantages to compressed air operated equipment is the ability to precisely “dial in” the performance by regulating the supply pressure. Consider an EXAIR Super Air Knife, for example. The flow & force can be adjusted from a “breeze to a blast” and any point in between, via a point-of-use Pressure Regulator. I know of users who operate them with a supply pressure as low as 5psig (that’s the “breeze”) and as high as 120psig (that’s the “blast”), depending on the requirements of the application.

EXAIR Stainless Steel Super Air Knives are popular in food processing applications (left to right): removing excess moisture prior to flash freezing of fish fillets, preventing clumping while packaging shredded cheese, and (my personal favorite) ensuring a consistent and even glazing of fresh, delicious doughnuts.

For a wide variety of typical industrial blowoff applications, a supply pressure of 80psig is a good place to start. So, it stands to reason that the compressed air header pressure will have to be at least 80psig. If the piping/distribution system is sized properly to carry the total amount of air flow you need to the points of use, though, it doesn’t need to be an awful lot higher than 80psig…and that’s a good thing. Here’s why:

Any fluid encounters friction as it flows through a pipe (or hose or tube) which causes a drop in pressure along every bit of the length of flow. The larger the pipe (or hose or tube) the lower the friction and hence, the lower the pressure drop. Now, that’s only important if you care about how much you’re spending on running your air compressor(s). Consider this:

We’ve got a customer that puts our Model 110042 42″ Aluminum Super Air Knives on machinery they make & sell to their customers. This Air Knife will use 121.8 SCFM when supplied at 80psig with the stock 0.002″ thick shim installed, and does the job quite well, most of the time. Some specific applications, however, need higher flow & force from the Air Knife, so our customer offers, as an option, the Super Air Knife with a 0.004″ thick shim installed. Since this doubles the air gap, it also doubles the air consumption. They’d plumbed the supply line to the Air Knife per the recommended in-feed pipe sizes from the Installation & Maintenance Guide:

Super Air Knife Kits include a Shim Set, Filter Separator, and Pressure Regulator.

Since the drop was less than 10ft long, they used a 3/4″ pipe, which was fine…until they installed the 0.004″ thick shim, which meant the air consumption doubled, to 243.6 SCFM. To get that much flow, at 80psig to the Air Knife, they had to increase their header pressure to 110psig, from the 90psig level at which they had been running. This was well within the operating parameters of their air compressor, but it made the compressor work harder, so it used more energy…and cost more to run. In fact, every 2psi increase in compressor discharge pressure results in a 1% increase in operating horsepower (source: Compressed Air & Gas Institute Compressed Air Handbook, chapter 4, page 8).

So, by increasing the discharge pressure by 20psi, the compressor’s power draw (and hence, operating cost) went up 10%. Now, I never found out what size their customer’s compressor was, but I DID look up prices for SCH40 black iron pipe, and for an 8ft length, the 1″ pipe was only $10-15 more than the 3/4″ pipe they were using. Since 243.6 SCFM is roughly 60HP worth of a typical industrial air compressor load (industry thumb rule says they use about 1HP to make 4 SCFM), we can assume that it’s at least a 75HP compressor. Using the following formula to calculate the operating cost while it’s drawing 80% of full load (while making a few reasonable assumptions):

Cost ($) = bhp x 0.746 x # of operating hours x $/kWh x % time x % full load bhp
motor efficiency

bhp = motor full load horsepower (frequently higher than nameplate HP but we’ll use nameplate 75HP to be conservative)
0.746 = conversion from hp to kW
# of operating hours (assume a month’s worth, 8 hours/day, 5 days/week, 4 weeks/month=800 hours)
$/kWh (assume $0.08/kWh)
% time = percentage of run time at this operating level (assume 85% of the time)
% full load bhp = brake horsepower as percentage of full load bhp at this operating level (assume 60HP load, 85%)
Motor efficiency = motor efficiency at this operating level (assume 95% fully loaded)

75HP x 0.746 x 800 x $0.08 x 0.85 x 0.85 = $2,723.29
.95

An additional 10% power draw changes the % full load bhp to 95%, and the cost for monthly operation is:

75HP x 0.746 x 800 x $0.08 x 0.95 x 0.85 = $3043.68
.95

That’s an extra $320.00 spent on running the compressor (per month) at 110psig discharge pressure, instead of an extra $15.00 spent on a larger pipe (one time cost) to run it at 90psig.

This is just one example of the effect of “artificial demand”, which is, essentially, wasted energy due to running your system at a higher pressure to compensate for undersized lines, leaks, intermittent high loads, etc. In addition to helping you specify the right supply line size for your compressed air operated products, we can assist with leak detection, intermediate storage, regulating supply pressures for differing loads, and replacing inefficient devices with engineered products. If you’d like to talk about any, or all, of that, give me a call.

Russ Bowman, CCASS

Application Engineer
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Using Accessories to Boost Your Tools

Published on by Russ BowmanLeave a comment

I was once on a local theater’s website, ordering tickets to an upcoming show that my wife and I were excited to see. I had the option to pay online and have a digital code emailed to me in lieu of a real live paper ticket. Can you believe they wanted to charge me almost $2 A TICKET for that?!? I adamantly refused (by that I mean I clicked the mouse extra hard on the “Will Call” button before completing my payment)…and saved that $4 (almost) for something REALLY important.

The night of the show, there was a 20-minute line at the Will Call window. Folks who had opted for the digital code were doing a quick scan with their smartphones and walking straight into the theater. I used the $4 I saved to partially pay for a $10 glass of wine from a concession kiosk in the lobby, as a peace offering for my lovely bride. That was indeed “something REALLY important.”

Another time, I was ordering a sump pump backup system for our house. I had the option of paying extra for the deluxe system, which came with all the fittings and a special tool to make installation a bit easier. Even though the ‘deluxe’ system adder was probably a bit more than the cost of the fittings from my local hardware store, I paid the “convenience fee” and got the deluxe system anyway. For the record, during the installation, I realized I would have bought an incorrect fitting at the local store which would have forced an emergency trip while I had the water turned off in my whole house. THAT was an inconvenience I was glad to have avoided.

Similarly, you can buy any EXAIR product with, or without, accessories that’ll make for simpler installation, improved performance, and to ensure it does what you want it to do. Some of these are product-specific, but many are suitable (and recommended) for use with any of our products:

Filter Separators

Good engineering practice calls for point of use filtration for any compressed air operated device. Even if you have the best intake & discharge filters on your air compressor, trace amounts of contaminants can sneak through, pipes can rust, and water vapor that the dryer doesn’t catch can condense. Particulates can build up and eventually clog the tight clearances in many engineered compressed air products, and if you’re using air for cleaning, drying, etc., keep in mind that whatever’s in your air will get on your product. Moisture isn’t always as big of a deal, but it can freeze inside Vortex Tubes, Spot Cooling Products, Cold Guns, and Cabinet Cooler Systems. That’s why we include Filter Separators in our Air Knife, Air Wipe, Static Eliminator Products, Line Vac, Adjustable Spot Cooler, Cold Gun, and Cabinet Cooler System Kits.

Automatic Drain Filter Separators come in sizes from 1/4 NPT to 1-1/4 NPT, for compressed air flows up to 400 SCFM.

Oil Removal Filters

These aren’t always needed, but we have them if your application calls for it. Some of the “usual suspects” are food & Pharma (see above “whatever’s in your air will get on your product”), blowoff prior to painting (the smallest amount of oil on the surface causes a phenomenon known as “fish eye” and it looks exactly like that sounds), or when your compressor is known to have oil carryover.

When properly installed downstream of an Automatic Drain Filter Separator (left,) an Oil Removal Filter (center) will provide clean, oil free air to the Pressure Regulator (right) and all downstream components.

Pressure Regulators

One of our Six Steps To Optimizing Your Compressed Air System is to control the air pressure at the point of use to minimize air consumption. In other words, find the supply pressure for your product that gets the job done, so you don’t use any more compressed air than you have to. Like the Filter Separators above, these come with many EXAIR Intelligent Compressed Air Product Kits.

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

Mounting Brackets and Coupling Kits

Most of our Filter Separators, Oil Removal Filters, and Pressure Regulators can be attached to a wall, panel, etc., with a Mounting Bracket, and can actually be attached to each other with a modular Coupling Kit. These parts simplify the installation, ensure they are oriented correctly, and minimize the chance for air leaks.

Filters (left) and Pressure Regulators (center) can be mounted using Brackets, and they can be connected together with Modular Couplers (right).

Silencing Mufflers

Many EXAIR products are engineered to develop a boundary layer of low velocity air flow that greatly reduces the sound level during operation. Other products use a venturi mechanism to draw a vacuum (Reversible Drum Vacs and E-Vac Vacuum Generators) or a Vortex Tube to generate cold air flow. The air flow from these products cannot be subjected to back pressure, and, without anything to mitigate the sound pressure generated by the rapid pressure drop as the air exits, they can be quite loud. For these, we have Silencing Mufflers that, except for the largest & most powerful of these products, reduce the sound level to be compliant with OSHA Standard 1910.95 Maximum Noise Exposure Limits.

From left to right… Reclassifying Mufflers offer the highest noise level reduction, eliminate oil mist, and come in sizes from 1/8 NPT to 1 NPT.
Sintered Bronze Mufflers are low cost and compact, with threads from #10-32 to 1-1/2 NPT.
Straight Through Mufflers use an internal sleeve of sound reducing foam, with threads from ¼ NPT to ¾ NPT, with male threads on one end and female threads on the other.
Heavy Duty Mufflers have an aluminum shell and an internal stainless steel screen that keeps contaminants like rust from being ejected in a dangerous way.  We have them in ¼ NPT and ¾ NPT sizes.

Shutoff and Solenoid Valves

Another one of our Six Steps To Optimizing Your Compressed Air System is to turn off the compressed air when it’s not in use. For this, EXAIR offers manual ball valves, for operator control, and Solenoid Valves, to automate the process.

Solenoid Valves (left) are available for 120VAC, 240VAC, and 24VDC in sizes from 1/4 NPT to 1 NPT. We offer manual Ball Valves in sizes from 1/8 NPT to 1-1/4 NPT.

Swivel Fittings, Stay Set Hoses, and Magnetic Bases

EXAIR Super Air Nozzles are threaded for installation with common air pipe & hose fittings. If the pipe isn’t pointed in the exact right direction, a Swivel Fitting gives you 50°  of adjustability. If the pipe isn’t quite close enough to what you want to blow off, Stay Set Hoses come in lengths of 6″ to 36″, and when bent to aim the Air Nozzle, they ‘stay set’, as advertised, until they need to be moved. If a pipe doesn’t exist and you need to run an air hose from the nearest drop on the header, Magnetic Bases can support the Air Nozzle and a Stay Set Hose to get the air where you want it. They even have shutoff valves to turn them off when they’re not in use (that’s a good thing; see above).

Save installation time AND get your blowoff pointed in the right direction!

Hoses and Compressed Air Fittings

If you need one of the aforementioned air hoses to reach a Magnetic Base or to supply a Safety Air Gun, we have two diameters to choose from – 3/8″ ID (1/4 MNPT threads on the ends) and 1/2″ ID (1/2 MNPT threads on the end), and we can make them to any length you need. And, while our selection probably isn’t quite as comprehensive as your local piping supply shop, we stock a number of pipe nipples, Couplers, Reducers, Tees, and Elbows that are commonly used with our products. So – like my backup sump pump deluxe kit, we can put all the fittings you may require in the same box for you.

Contact an Application Engineer if you have ANY questions about how to properly supply compressed air to your EXAIR products.

At EXAIR, we’re here to make sure you get the most out of our products, and your compressed air system. If you need accessories to help with that, give me a call.

Russ Bowman, CCASS

Application Engineer
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Pressure Drop vs Differential Pressure

Published on by John BallLeave a comment

I find myself interchanging these terms; pressure drop and differential pressure.  This is very common as both are determined by the change in pressure between two points.  In this blog, I will cover the difference between these two terms in my view.

Pressure drop only occurs when the air is flowing.  The higher the velocity, the more extreme the pressure drop will be.  Velocity is created when the pressure changes.  So, the higher pressure will go toward the lower pressure.  But we wish for that pressure difference to be as low as possible.  Pressure drop is always a loss, and you cannot regain that energy.  Forms of pressure drop that can be found are like small diameter pipes or tubing; restrictive fittings like quick disconnects, and conditioning equipment like after coolers and air dryers.  If too large of a pressure drop occurs, the pneumatic equipment will not have enough power to operate effectively and efficiently.  I have another blog with a video that helps demonstrate this, “Pressure Drop and its Relationship to Compressed Air”. 

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

Differential pressure can be static or flowing.  It is very similar to pressure drop except that the energy is stored.  The most common device that does this is the pressure regulator.  You are able to reduce the pressure downstream to the point-of-use.  This type of pressure reduction stores energy, and it will save you money, instead of wasting money.  For every 10 PSI reduction in pressure, it will save you 5% in energy.  With blow-off devices, you want to use the least amount of pressure to “do the job”.  Over-using your compressed air is wasteful.

Here is a graph of a typical compressed air system.  As you can see, the typical pressure drop from the air compressor to the point-of-use.  So, if you can reduce the pressure drop through the system and optimize the differential pressure from the regulator to your point-of-use, you can optimize your system.

Pressure Drop Chart

In a simple statement, a pressure drop loses energy while differential pressure stores energy for later use.  EXAIR offers a variety of efficient, safe, and effective compressed air products to fit within the demand side.  This will include the EXAIR Super Air Knives, Super Air Nozzles, and Safety Air Guns.  If you wish to go further in optimizing your system, an Application Engineer at EXAIR will be happy to help you.

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb

Pressure Drop Chart by Compressed Air Challenge Organization.

“Under Pressure” Pressure Regulators!

Published on by Jordan T ShouseLeave a comment

I recently recommended to a customer to turn their air pressure down on their system as low as their process would allow. Meaning regulate the pressure so you have enough to complete the operations needed but find that happy medium where your compressor isn’t working as hard to build those high pressures for no reason!

Compressed air is an amazing tool to have, and when used properly it can be more efficient that other non-compressed air tools that run off electricity. However, it’s pretty common to see compressed air systems running at their max just because.

Pressure Regulators “dial in” performance to get the job done without using more air than necessary.

Lowering the air system pressure reduces the compressor power consumption by about 1% for every two psi of lower pressure. Lowering the pressure also makes any unregulated operations reduce consumption by almost 1% for every one psi of pressure reduction. Not to mention the extra savings if your compressor system can turn down the compressor power because of the reduced flow and possibly shut off compressors that are no longer needed!

The best pressure at which to set your system is the level where your production can operate efficiently and effectively without waste: There is no right pressure—it depends on your operations and tools. You may have 90 to 100 psig at the compressor, but at the production machine, where the actual work is being done, you could have only 65 to 70 psig. In some cases, it may be even lower due to pressure drops in undersized piping, filters, regulators. The goal is to lower compressor discharge pressure without affecting the the operations at the end of the line.

Having artificially high plant-pressure can help you deal with surges in compressed air demand that might occasionally cause low-pressure and affect production. The higher pressure acts to store reserve air in the various volumes made up of receivers, pipes and such in your system. However, the higher pressure costs more to produce and makes unregulated end uses consume more air, which is an expensive trade-off. Another option is to make sure you have line pressure regulators at each point of use. This will allow you to regulate the operation to the pressure needed being sure to save compressed air and keep the over all system running more efficient.

You can regulate those point of use lines with a number of EXAIRs Pressure Regulators!

EXAIR offers a range of Pressure Regulators capable of handling air flow of up to 700 SCFM.

If we can help size a regulator, or have any other questions on how EXAIR can help you save compressed air in your system please reach out to me or one of our other Application Engineers!

Jordan Shouse
Application Engineer

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