There is hardly a day I work that I am not talking about the importance of properly installed pressure gauges. These small devices can often get overlooked or thought of as not necessary on an installation. When troubleshooting or evaluating the compressed air consumption of an application, this is one of the first items I look for in the installation.
As Russ Bowman shows in the above video discussing proper piping sizes, you can see the importance of properly placed pressure gauges. This shows the worst-case scenario where the pressure drop due to improper line sizes gives the false sense to the operator that they are achieving full line pressure when in fact they are not. In order to accurately measure consumption rates, pressure AT THE INLET (within a few feet) to any compressed air product is necessary, rather than upstream at a point where there may be restrictions or pressure drops between the inlet and the gauge. So how exactly do these analog gauges measure the pressure of the compressed air at the installed locations?
The video below shows a great example of pressure increasing and decreasing moving the Bourdon tube that is connected to the indicating needle. The description that follows goes more in-depth with how these internals function.
Most mechanical gauges utilize a Bourdon-tube. The Bourdon-tube was invented in 1849 by a French watchmaker, Eugéne Bourdon. The movable end of the Bourdon-tube is connected via a pivot pin/link to the lever. The lever is an extension of the sector gear and movement of the lever results in rotation of the sector gear. The sector gear meshes with spur gear (not visible) on the indicator needle axle which passes through the gauge face and holds the indicator needle. Lastly, there is a small hairspring in place to put tension on the gear system to eliminate gear lash and hysteresis.
When the pressure inside the Bourdon-tube increases, the Bourdon-tube will straighten. The amount of straightening that occurs is proportional to the pressure inside the tube. As the tube straightens, the movement engages the link, lever, and gear system that results in the indicator needle sweeping across the gauge.
If you would like to discuss pressure gauges, the best locations to install them, or how much compressed air an application is using at a given pressure, give us a call, email, or chat.
EXAIR uses our blog platform to communicate everything from new product announcements to personal interests to safe and efficient use of compressed air. We have recently passed our 5 year anniversary of posting blogs (hard for us to believe) and I thought it appropriate to share a few of the entries which explain some more of the technical aspects of compressed air.
Here is a good blog explaining EXAIR’s 6 steps to optimization, a useful process for improving your compressed air efficiency:
One of the Above 6 steps is to provide secondary storage, a receiver tank, to eliminate pressure drops from high use intermittent applications. This blog entry addresses how to size a receiver tank properly:
Thanks for supporting our blog over the past 5 years, we appreciate it. If you need any support with your sustainability or safety initiatives, or with your compressed air applications please contact us.
When installing a compressed air driven device, there is almost nothing more important than proper plumbing. Inadequate compressed air supply can cause performance issues which lead to rejected product or machine slowdown. In each of these cases, the end result is a loss in productivity and profitability.
At EXAIR, we understand the ins and outs of proper compressed air plumbing. Over time, I’ve made a list of the most common plumbing mistakes and how to avoid them.
Quick disconnects: While tempting and lighting fast, these fittings can limit the amount of compressed air delivered through the orifice of the fitting. If you have performance concerns, check for pressure drops across a quick disconnect fitting.
Inadequate line size: Think of the compressed air line as a water hose. If the hose gets too long or is restricted or too small, there won’t be enough force and flow to do any work. Many compressed air installations use schedule 40 pipe, and the ID and OD dimensions of this pipe are not always what you would think. Engineering Toolbox is a favorite site of mine and they have a handy chart about Schedule 40 pipe here. Always make sure the compressed air line can flow enough air volume for the application.
Pressure drops: Both of the above mentioned problems are essentially pressure drop related issues, but often there are oversights such as the distance of the compressed air line. As the length of the line increases, the pressure drop will increase. Imagine trying to blow air through a 1 ft section of garden hose. Not too hard, right. Now imagine trying to blow through 50 ft of garden hose. No matter how hard you try, all the energy will be lost along the length of the hose. Double check your line lengths and corresponding pressure drops.
No gauges: If you’re operating a compressed air device and you depend on that unit for proper production, it is imperative to know the operating pressure at the unit. This is why EXAIR includes pressure gauges with any kit containing a pressure regulator. There may be 110 PSIG available at the main line, but a gauge at the device will register pressure to the device, which will generally be slightly lower. (This is also helpful to locate any of the aforementioned pressure drops)
Excessive piping bends: Each bend in a compressed air line (especially 90° bends) removes energy from the compressed air. Make sure the line to the point of use is as direct and free as possible.
PSI vs. SCFM: When sizing a compressed air device or system, it’s important to size based on the SCFM and PSI ratings of the compressor. A compressor that produces 100 PSI cannot necessarily operate any device that requires 100 PSI. Be sure your compressor has adequate PSI and SCFM ratings for the needs of the application.
As a general rule, we always advise to consult with an EXAIR Application Engineer regarding application specific questions. Whether product orientation or plumbing, we are always available to answer your questions.