Installing a Secondary Receiver Tank

Picture by Clker-Free-Vector licensed by Pixabay

We often run into situations where a customer does not have enough compressed air volume to implement a solution. This leaves three possible options. 1) Abandon the project all together and continue to feel the pain the problem creates. 2) Install a larger compressor, with associated expense. 3) Install a secondary, or “point of use” receiver tank to store the compressed air volume local to the application, to be available immediately without having to rely on the distribution system for storage capability. This 3rd option is a cost-effective solution customers often use to mitigate the impact of installing a new compressed air consuming product onto the system.

Large demand events on a compressed air system can leave the system short on air. This can result in a system pressure drop which is undesirable. Utilizing a secondary receiver tank to mitigate the impact of larger volume consuming events is a common and useful strategy that many compressed air professionals will recommend and pursue. In this kind of scenario, the receiver tank acts much like a capacitor in a camera flash. A camera battery charges a capacitor which then dumps its charge into the flash bulb when you take a photo for a notably bright flash which is what one generally wants from their camera flash.

In this same way, a receiver tank acts like the capacitor to “dump” the air volume needed to make a compressed air device work at its design pressure and flow for some prescribed period of time. In situations like this, the high demand does need to be an intermittent one so that the tank can then re-charge from the compressor system and be ready for the next air use event. This means that certain calculations need to be made to ensure that the receiver tank is sized properly to provide the desired effect.

How do you size a receiver tank? Here’s the calculation to determine the proper size:

Let’s consider an example of an Air Amplifier solution. A customer wants to blow on hot metal parts coming out of an oven to cool them down as an “air quench”. We evaluate the application and determine that (2) 2″ Super Air Amplifiers will provide the right amount of flow. Those units are going to operate at 60 PSIG to provide the desired effect. (2) 2″ Super Air Amplifiers will consume 24.5 SCFM @ 60 PSIG. Each batch of parts comes out of the oven at a rate of one batch every 5 minutes. They want to provide the necessary cooling for a total of 30 seconds to have the air quench effect. So, every 5 minutes, the Air Amplifiers will be blowing for 1/2 minute. Each “on” event consumes 12.25 Standard Cubic Feet of air. We then have 4 minutes, 30 seconds left to re-plenish the tank.

The last piece of information we need to know is the system pressure for the compressed air header feeding the tank. The system pressure is 120 PSIG. And so, our calculation looks like this:

V = 0.5 min. x 24.5 rate of flow x (60 PSIG + 14.5 PSIA)

V = 913

V = 15.2 ft.3

There are 7.48 gallons to a cubic foot, so our receiver tank in this example would be
15.2 ft.3 x 7.48 = 114 gallons.

Given the fact that receiver tanks are made in certain, standard sizes, a 120 gallon tank or two, 60 gallon tanks piped in upstream of the compressed air load would be appropriate for this application.

As a further note to the example, the refill rate to the tank(s) would need to be a minimum of 2.72 SCFM to get the volume replenished in time for the next event. This is less than 1 HP of industrial air compressor to maintain such a flow rate to refill the tank.

With some reasonably simple math to determine tank size, and a willingness to pursue this kind of air delivery solution, you can implement that compressed air solution at a fraction of the cost compared to a new compressor.

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Cover Photo by dkeissling and licensed by Pixabay

Data: Not the Cyborg from Star Trek, Air Data

This world is a constant gathering of data anymore. Every item that connects to the internet moves data, collects data, and shares data. The problem is often, what data is truly needed and what we can do with it. When it comes to business analytics and data there are many types. The same can be said for compressed air.

green and white line illustration
Photo by Markus Spiske on

When looking at the data your compressed air system is collecting and what data matters, it is good to understand the types of data we could be dealing with and what could be detrimental. That’s right, too much data can be a bad thing. Or data that hasn’t been refined and is coming in not in the correct format can also be crippling to analysis. The first is too much data and be considered “Vampire” Data, there is so much there that it just simply sucks all the energy out of your analysis and can lead to paralysis through analysis. The second would be considered “Dirty” data. This data causes lots of additional work to clean up and process. Rather than just importing, running with it, and being able to take off, it generates many of its own work levels and may even have erroneous readings in it throughout that can also cause issues. So how can we identify these within our compressed air system?

What could vampire data in a compressed air system look like? Well, multiple Flowmeters collecting data on the same branch line without any offshoots would be the first. If you have a loop-style main, there would be no need to measure the flow coming out of your dry storage and going into the header loop, then measure the header flow again before the first drop. A second instance would be taking measurements in a high quantity during system downtimes, this could be the off-hours period, and there isn’t a need to monitor every second if nothing is running. Now, monitoring overnight is needed, this helps to monitor leaks or other phantom draws of air while equipment is not running. It doesn’t need to be monitored every second of the off hours though. So try to keep this nuisance to a minimum and if you aren’t sure where you should install Digital Flowmeters, contact an Application Engineer to discuss.

The latter, dirty data, is sometimes harder to take care of. This can be caused by different sources all feeding data into separate files or even importing routines from equipment not being refined. This can also be due to operator error when collecting manual data points or not following standard operating procedures. One way to reduce the number of items to import data from is by utilizing equipment like Digital Flowmeters with Wireless Capabilities and also pressure-sensing flow meters. These all help to reduce the number of items or routines in a compressed air system data collection. Again, if you aren’t sure how to clean up data, or how to process the data coming out of our EXAIR Logger software that is included with the Wireless Capability Digital Flow meter, that’s what we are here to help with.

No matter what, data in a compressed air system is important and helps to create system profiles, deduce failed equipment, refine processes, and most of all give you the ability to calculate ROI after installing engineered solutions. If you want to discuss how to do this, reach out to an Application Engineer today!

Brian Farno
Application Engineer

Basics of Entrainment

EXAIR Super Air Nozzle entrainment

EXAIR has many choices for compressed air savings. EXAIR specifically takes pride in engineering products that not only save compressed usage when comparing to your existing processes but also considers the entrainment of ambient air compounding the compressed savings. Entrainment? Well think of it like this; We love “free” perks when using our reward cards at stores, gas stations or restaurants. Although you are paying the initial cost of whatever you are buying its nice knowing there is a “free” reward. We know producing compressed air is expensive, so we like that we have entrained savings when using our products.

EXAIR Super Air Knives are a perfect example of getting a reward when paying for your compressed air. Super Air Knives will entrain up to 40:1 ambient “free” air, so essentially you gain 40 SCFM of ambient air for every 1 SCFM being used. The illustration below shows more about our Super Air Knife.

Bernoulli’s equation takes into account four main variables which are Pressure (P), Density (r), Velocity (v), and a height difference (z); along with a single constant for gravity. The relationship between the velocity squared and the pressure from the equation above.  Being that this relationship is a constant along the streamline; when the velocity increases; the pressure has to come down. Now we have to look at how fluids like to behave. Fluids within a system like to be at a constant pressure when at the same height and reach a state of equilibrium. This means that fluids will always flow towards a low pressure area, which means that if you create a constant low pressure area you can amplify the air stream. This is the same principle as to why airplanes can fly.

Bernoulli’s Equation

EXAIR used the Bernoulli Principle when designing our Air Amplifiers, Air Knives, Air Wipes, Air Nozzles/Jets, Safety Air Guns and Static Eliminating Products. We not only designed in safety into our products but also the reward of “free” air or entrained air. If you would like to take advantage of the effects of air entrainment to improve your application blowing and cooling needs, we would like to be your first stop. Please contact any of our qualified Application Engineers for help with your application today!

Eric Kuhnash
Application Engineer
Twitter: Twitter: @EXAIR_EK

Digital Flow Meter Options Make it Easier to Manage What You Measure

“You can’t manage what you don’t measure” is a widely used maxim, in a number of fields. Since EXAIR is in the business of helping customers get the most out of their compressed air system, we use it with regard to our Digital Flowmeters.

While installation of our standard Digital Flowmeters is fairly easy & straightforward, it does require depressurization of the pipe you’re installing it onto to drill the holes for the probes. If you can do that, installation takes a matter of minutes, you can repressurize the line and get back to work. If it’s impossible, impractical, or even inconvenient to isolate and depressurize the pipe, our Hot Tap models allow for installation under full line pressure. Not only do you get away with not depressurizing part of your system, you don’t even have to stop using compressed air loads being supplied by that pipe. Here’s how it works:

  • Like any mass thermal type flow meter, these work by inserting two probes through the pipe wall. One is heated to a specific temperature, and the other measures the temperature of the air flowing past it. The difference is proportional to the mass flow rate through the pipe.
  • Normally, drilling holes in a pressurized pipe is a BAD idea. The bases for the Hot Tap Digital Flowmeters, however, allow you to do it safely. They have valves in them, which the drill bit passes through, that you’ll close as you withdraw the drill bit to prevent compressed air from flowing out.
  • A muffler in the drill guide lowers the sound level to a slight hiss, and collects the chips made by the drill bit.
  • Once the Digital Flowmeter itself is installed on the Hot Tap base, the valves are opened to put the Digital Flowmeter in service.
Hot Tap Digital Flowmeters are available for 2″ through 8″ iron pipe, , and 2″ through 4″ copper pipe.

As beneficial as it is to measure the mass flow rate through the pipe, it can be important to know the pressure inside the pipe as well. Our Pressure Sensing Digital Flowmeters provide for this, with a 2nd milliamp output.

Pressure Sensing Digital Flowmeters can be installed on 2″ through 8″ iron pipe, or on 2″ through 4″ copper pipe (above left). They provide input to the Flowmeter’s 2nd milliamp output via a special sensing port (above center). They can display either flow or pressure values on their display, or you can use our optional Wireless Capability (above right) to transmit this data to your computer.

A pressure AND flow profile can aid in identifying areas for improvement…and sometimes even finding problems that need fixing. One of our customers did just that, by using the flow & pressure profile to identify a transient caused by a faulty filter baghouse cleaning cycle control.

If you’re serious about getting the most out of your compressed air use, the very first step in EXAIR’s Six Steps To Optimizing Your Compressed Air System is literally a great place to start.

Six Steps to Optimizing Your Compressed Air System

To find out more, give me a call.

Russ Bowman, CCASS

Application Engineer
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