How-To Size Receiver Tanks and Why Use Them in Your Compressed Air System

Receiver Tank

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 the operation of your compressed air system.  The primary receiver tanks help to protect the supply side when demands are high, and the secondary receiver tanks help pneumatic systems on the demand side for optimum 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 for this is to have a ready source of energy to increase efficiency and speeds with the ebbs and flows of electrical signals.  The same can be said for a pneumatic system with secondary receiver tanks.

To tie this into the compressed air system, if you have an area that requires a high volume of compressed air intermittently, a secondary receiver tank would benefit this type of pneumatic setup.  With valves, cylinders, actuators, and pneumatic controls which turn on and off, it is important to have a ready source of stored “energy” nearby.

For calculating a minimum volume size for your secondary receiver tank, we can use Equation 1 below.  It is the same for sizing a primary receiver tank, but the scalars are slightly different.  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 tank volume that would be needed.  The other value in the equation 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 P2P1 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 receiver tank with a larger volume would work as a secondary receiver tank.

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.  EXAIR stocks 60 Gallon tanks, model 9500-60, to add to those specific areas.  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 your efficiency and speed back into your applications.

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

Photo: Circuit Board courtesy from T_Tide under Pixabay License

How to Manage Condensate in Your Compressed Air System

If you operate an air compressor, you’re drawing water vapor into your compressed air system.  Factors like climate control (or lack thereof,) and humidity will dictate how much.  If (or more to the point, when) it condenses, it becomes an issue that must be addressed.  There are several types of dryer systems to choose from, usually when you buy your compressor…we’ve covered those in a number of blogs.  Some of these can leave a little more water vapor than others, but remain popular and effective, when considering the cost, and cost of operation, of the different types.

So, how do you handle the condensate that the dryer doesn’t remove?

  • Receivers, or storage tanks (like EXAIR Model 9500-60, shown to the right,) are commonly used for several reasons:
    • By providing an intermediate storage of compressed air close to the point of use, fluctuations across the system won’t adversely affect an application that needs a constant flow and pressure.
    • This also can keep the air compressor from cycling rapidly, which leads to wear & tear, and additional maintenance headaches.
    • When fitted with a condensate drain (more on those in a minute,) they can serve as a wet receiver.  Condensate collects in the bottom and is manually, or automatically emptied.
  • Condensate drains, while popularly installed on receivers, are oftentimes found throughout larger systems where the vapor is prone to condense (intercoolers, aftercoolers, filters and dryers) and where the condensation can be particularly problematic (drip legs or adjacent to points of use.) There are a couple of options to choose from, each with their own pros & cons:
    • Manual drains are self explanatory: they’re ball valves; cycled periodically by operators.  Pros: cheap & simple.  Cons: easy to blow down too often or for too long, which wastes compressed air.  It’s also just as easy to blow down not often enough, or not long enough, which doesn’t solve the condensate problem.
    • Timer drains are self explanatory too: they cycle when the timer tells them to. Pros: still fairly cheap, and no attention is required.  Cons: they’re going to open periodically (per the timer setting) whether there’s condensate or not.
    • Demand, or “zero loss” drains collect condensate until their reservoir is full, then they discharge the water.  Pros: “zero loss” means just that…they only actuate when condensate is present, and they stop before any compressed air gets out.  Cons: higher purchase price, more moving parts equals potential maintenance concerns.
  • The “last line of defense” (literally) is point-of-use condensate removal.  This is done with products like EXAIR Automatic Drain Filter Separators.  They’re installed close to compressed air operated devices & products, oftentimes just upstream of the pressure regulator and/or flow controls…the particulate filter protects against debris in these devices, and the centrifugal element “spins” any last remaining moisture from the compressed air flow before it gets used.

Good engineering practice calls for point of use filtration and moisture removal, such as that provided by EXAIR Filter Separators.

Efficient and safe use of your compressed air includes maintaining the quality of your compressed air.  If you’d like to find out more about how EXAIR Corporation can help you get the most out of your compressed air system, give me a call.

Russ Bowman
Application Engineer
EXAIR Corporation
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Six Steps to Optimization, Step 4 – Turn Off Your Compressed Air When Not in Use

Step 4 of the Six Steps To Optimizing Your Compressed Air System is ‘Turn off the compressed air when it isn’t in use.’  Click on the link above for a good summary of the all the steps.

6 Steps from Catalog

Two basic methods to set up a compressed air operation for turning off is the ball valve and the solenoid valve. Of the two, the simplest is the ball valve. It is a quarter turn, manually operated valve that stops the flow of the compressed air when the handle is rotated 90°. It is best for operations where the compressed air is needed for a long duration, and shut off is infrequent, such as at the end of the shift.

manual_valves (2)
Manual Ball Valves, from 1/4 NPT to 1-1/4 NPT

The solenoid valve offers more flexibility. A solenoid valve is an electro-mechanical valve that uses electric current to produce a magnetic field which moves a mechanism to control the flow of air. A solenoid can be wired to simple push button station, for turning the air flow on and off – similar to the manual valve in that relies on a person to remember to turn the air off when not needed.

wa_solvalv
A Wide Array of Solenoid Valve Offerings for Various Flows and Voltage Requirements

Another way to use a solenoid valve is to wire it in conjunction with a PLC or machine control system. Through simple programming, the solenoid can be set to turn on/off whenever certain parameters are met. An example would be to energize the solenoid to supply an air knife when a conveyor is running to blow off parts when they pass under. When the conveyor is stopped, the solenoid would close and the air would stop blowing.

The EXAIR EFC (Electronic Flow Control) is a stand alone solenoid control system. The EFC combines a photoelectric sensor with a timer control that turns the air on and off based on the presence (or lack of presence) of an object in front of the sensor. There are 8 programmable on/off modes for different process requirements. The use of the EFC provides the highest level of compressed air usage control. The air is turned on only when an object is present and turned off when the object has passed by.

efcapp
EFC Used To Control Bin Blow Off Operation

By turning off the air when not needed, whether by a manual ball valve, a solenoid valve integrated into the PLC machine control or the EXAIR EFC, compressed air usage will be minimized and operation costs reduced.

If you have questions about the EFC, solenoid valves, ball valves or any of the 15 different EXAIR Intelligent Compressed Air® Product lines, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer
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EXAIR Accessories – We’ve Got you Covered

When you work with us here at EXAIR, we strive to have all the ancillary items that you might need to make your installation a success, without having to find components at the last minute or perhaps using the wrong sized components. Each specific product line such as Super Air Knives or Line Vac air operated conveyors have specific accessories such as mounting brackets or plumbing kits which EXAIR has made to simplify the installation of those particular products. We also carry generalized accessories which work across all of the product lines so you do not have to use multiple vendors or purchase orders.

Silencing Mufflers – Per OSHA Standard 1910.95(a), a worker must not be exposed to sounds levels above 90 dBA for any eight hour shift of a 40 hour work week.  EXAIR offers several types of mufflers including – Reclassifying, Sintered Bronze, Straight-Through and Heavy Duty.  For reducing the noise associated with an EXAIR E-Vac Generator, Vortex Tube, Cabinet Cooler System, or the exhaust air from cylinders, valves and other air powered equipment, we’ve got a muffler that will help to keep the noise level at an acceptable level.

Mufflers

Solenoid and Manual Valves – The easiest way to reduce compressed air usage and save on operating expense is to turn off the compressed air to a device when it isn’t needed. EXAIR carries a wide assortment of solenoid valves, with offerings in the NEMA 4/4X classification, and supply voltages of 24VDC, 120VAC, and 240VAC.  We also have manual ball valves from 1/4 NPT to 1-1/4 NPT and a foot operated valve, with 1/4 NPT connections.

Valves

Swivel Fittings, Stay Set Hoses and Magnetic Bases – To provide a great degree of flexibility for positioning an EXAIR Super Air Nozzle, Air Jets or Air Amplifiers, EXAIR offers several items.  The Swivel Fittings have 25 degree of movement from the center axis, providing a total of 50 degree of adjustability.  The position is locked in place and holds until adjustment is needed. For applications where frequent re-positioning of the air device is required, the Stay Set Hoses are ideal.  Simply mount the hose close to the application, bend it to the shape preferred, and because the hose has “memory”, it will not creep or bend.  Lastly, the Magnetic Bases are another option for flexible, movable installations.  The base has a on/off valve, and a powerful magnet to hold in any vertical or horizontal mounting arrangement.

Swivels, StaySets,MagBases2

 

Hoses – EXAIR can provide hoses for your application.  For the Line Vac air operated conveyor applications, we offer conveyance hose – a durable, clear reinforced PVC hose, in diameters of 3/8″ to 3″ ID, and lengths up to 50′. On the compressed air side, we can provide 12′ Coiled Hoses with 1/8, 1/4, and 3/8 NPT connections, and also 3/8″ and 1/2″ ID hose in lengths to 50′.

Hoses

Filter Separators, Oil Removal Filters and Pressure Regulators – Perhaps the most important accessories for use on a compressed air device are filters and regulators. Filtering the compressed air of dirt, debris, moisture and oil will help to prevent build up inside the EXAIR products, leading to longer service life, and less time spent cleaning, while providing optimum performance. Regulating the air pressure allows for tuning of the performance, using the proper amount of compressed air to obtain satisfactory results.

Filter and Regualtors

If you have questions regarding accessories for use with any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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