How to Size a Receiver Tank and Improve your Compressed Air System

Receiver Tank: Model 9500-60

My colleague, Lee Evans, wrote a blog about calculating the size of primary receiver tanks within a compressed air system.  (You can read it here: Receiver Tank Principle and Calculations).  I would like to expand a bit more about secondary receiver tanks.  They can be strategically placed throughout the plant to improve your compressed air system.  The primary receiver tanks help to protect the supply side when demands are high, and the secondary receiver tanks help systems on the demand side to optimize performance.

Circuit Board

I like to compare the pneumatic system to an electrical system.  The receiver tanks are like capacitors.  They store energy produced by an air compressor like a capacitor stores energy from an electrical source.  If you have ever seen an electrical circuit board, you notice many capacitors with different sizes throughout the circuit board (reference photo above).  The reason is to have a ready source of energy to increase efficiency and speed for the ebbs and flows of electrical signals.  The same can be said for the secondary receiver tanks in a pneumatic system.

To tie this to a compressed air system, if you have an area that requires a high volume of compressed air intermittently, a secondary receiver tank would benefit this system.  There are valves, cylinders, actuators, and pneumatic controls which turn on and off.  And in most situations, very quickly.  To maximize speed and efficiency, it is important to have a ready source of air nearby to supply the necessary amount quickly.

For calculating a minimum volume size for your secondary receiver tank, we can use Equation 1 below.  It is the same as sizing a primary receiver tank, but the scalars are slightly different.  The secondary receivers are located to run a certain machine or area.  The supply line to this tank will typically come from a header pipe that supplies the entire facility.  Generally, it is smaller in diameter; so, we have to look at the air supply that it can feed into the tank.  For example, a 1” NPT Schedule 40 Pipe at 100 PSIG can supply a maximum of 150 SCFM of air flow.  This value is used for Cap below.  C is the largest air demand for the machine or targeted area that will be using the tank.  If the C value is less than the Cap value, then a secondary tank is not needed.  If the Cap is below the C value, then we can calculate the smallest volume that would be needed.  The other value is the minimum tank pressure.  In most cases, a regulator is used to set the air pressure for the machine or area.  If the specification is 80 PSIG, then you would use this value as P2.  P1 is the header pressure that will be coming into the secondary tank.  With this collection of information, you can use Equation 1 to calculate the minimum tank volume.  So, any larger volume would fit the requirement as a secondary receiver tank.

Secondary Receiver tank capacity formula (Equation 1)

V = T * (C – Cap) * (Pa) / (P1-P2)

Where:

V – Volume of receiver tank (cubic feet)

T – Time interval (minutes)

C – Air demand for system (cubic feet per minute)

Cap – Supply value of inlet pipe (cubic feet per minute)

Pa – Absolute atmospheric pressure (PSIA)

P1 – Header Pressure (PSIG)

P2 – Regulated Pressure (PSIG)

If you find that your pneumatic devices are lacking in performance because the air pressure seems to drop during operation, you may need to add a secondary receiver to that system.  For any intermittent design, the tank can store that energy like a capacitor to optimize the performance.  EXAIR stocks 60 Gallon tanks, model 9500-60 to add to those specific locations, If you have any questions about using a receiver tank in your application, primary or secondary, you can contact an EXAIR Application Engineer.  We can restore that efficiency and speed back into your application.

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

 

Photo: Circuit Board courtesy from T_Tide under Pixabay License

6 Steps to Optimizing Your Compressed Air System

If you’re a follower of the EXAIR Blog, you’re probably well aware that compressed air is the most expensive utility in an industrial environment. The average cost to generate 1000 Standard Cubic Feet of compressed air is $0.25. If you’re familiar with how much air you use on a daily basis, you’ll understand just how quickly that adds up.

To make matters worse, many compressed air systems waste significant amounts of compressed air just through leaks. According to the Compressed Air Challenge, a typical plant that has not been well maintained will likely have a leak rate of approximately 20%!! Good luck explaining to your finance department that you’re carelessly wasting 20% of the most expensive utility.

SBMart_pipe_800x

6 Steps from Catalog

The best way to save energy associated with the costs of generating compressed air is pretty straightforward and simple: TURN IT OFF! Placing valves throughout your distribution system allows you to isolate areas of the facility that may not need a supply of compressed air continuously.

Even a well-maintained system is going to have a leakage rate around 10%, it’s darn near impossible to absolutely eliminate ALL leaks. By having a valve that allows you to shut off the compressed air supply to isolated areas, you’re able to cut down on the potential places for leaks to occur.

You’re likely not running each and every machine continuously all day long, if that’s the case why not shut off the air supply to those that aren’t running? When operators go to lunch or take a break, have them turn off the valves to prevent any wasted air. The fact of the matter is that taking this one simple step can truly represent significant savings when done diligently.

You wouldn’t leave your house with all the lights and TV on, so why leave your compressed air system running when it’s not in use? Even if everyone’s left for the day, leaks in the system will cause the compressor to keep running to maintain system pressure.

Taking things one step further, EXAIR’s Electronic Flow Control (EFC) utilizes a solenoid controlled by photoelectric sensor that has the ability to shut off the compressed air when no part is present. If you’re blowing off parts that are traveling along a conveyor with space in between them, there’s no need to continuously blow air in between those parts. The EFC is able to be programmed to truly maximize your compressed air savings. The EFC is available in a wide range of different capacities, with models from 40-350 SCFM available from stock and systems controlling two solenoid valves for larger flowrates available as well.

newEFC2_559

It’s no different than turning off your house lights when you leave for work each day. Don’t get caught thinking compressed air is inexpensive “because air is free”. The costs to generate compressed air are no joke. Let’s all do our part to reduce energy consumption by shutting off compressed air when it isn’t necessary!

Tyler Daniel
Application Engineer
E-mail: TylerDaniel@EXAIR.com
Twitter: @EXAIR_TD