Receiver Tank Principle and Calculations

 

Visualization of the receiver tank concept

A receiver tank is a form of dry compressed air storage in a compressed air system.  Normally installed after drying and filtration, and before end use devices, receiver tanks help to store compressed air.  The compressed air is created by the supply side, stored by the receiver tank, and released as needed to the demand side of the system.

But how does this work?

The principle behind this concept is rooted in pressure differentials.  Just as we increase pressure when reducing volume of a gas, we can increase volume when reducing pressure.  So, if we have a given volume of compressed air at a certain pressure (P1), we will have a different volume of compressed air when converting this same air to a different pressure (P2).

This is the idea behind a receiver tank.  We store the compressed air at a higher pressure than what is needed by the system, creating a favorable pressure differential to release compressed air when it is needed.  And, in order to properly use a receiver tank, we must be able to properly calculate the required size/volume of the tank.  To do so, we must familiarize ourselves with the receiver tank capacity formula.

An EXAIR 60 gallon receiver tank

Receiver tank capacity formula

V = ( T(C-Cap)(Pa)/(P1-P2) )

 

Where,

V = Volume of receiver tank in cubic feet

T = Time interval in minutes during which compressed air demand will occur

C = Air requirement of demand in cubic feet per minute

Cap = Compressor capacity in cubic feet per minute

Pa = Absolute atmospheric pressure, given in PSIA

P1 = Initial tank pressure (Compressor discharge pressure)

P2 = minimum tank pressure (Pressure required at output of tank to operate compressed air devices)

An example:

Let’s consider an application with an intermittent demand spike of 50 SCFM of compressed air at 80 PSIG.  The system is operating from a 10HP compressor which produces 40 SCFM at 110 PSIG, and the compressed air devices need to operate for (5) minutes at this volume.

We can use a receiver tank and the pressure differential between the output of the compressor and the demand of the system to create a reservoir of compressed air.  This stored air will release into the system to maintain pressure while demand is high and rebuild when the excess demand is gone.

In this application, the values are as follows:

V = ?

T = 5 minutes

C = 50 CFM

Cap = 40 SCFM

Pa = 14.5 PSI

P1 = 110 PSIG

P2 = 80 PSIG

Running these numbers out we end up with:

This means we will need a receiver tank with a volume of 24.2 ft.³ (24.2 cubic feet equates to approximately 180 gallons – most receiver tanks have capacities rated in gallons) to store the required volume of compressed air needed in this system.  Doing so will result in a constant supply of 80 PSIG, even at a demand volume which exceeds the ability of the compressor.  By installing a properly sized receiver tank with proper pressure differential, the reliability of the system can be improved.

This improvement in system reliability translates to a more repeatable result from the compressed air driven devices connected to the system.  If you have questions about improving the reliability of your compressed air system, exactly how it can be improved, or what an engineered solution could provide, contact an EXAIR Application Engineer.  We’re here to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Replacing Liquid Nozzles with Engineered Air Nozzles

I wrote a blog a few weeks ago about increasing efficiency with EXAIR Super Air Nozzles.  In the application for that blog we used engineered nozzles to place open pipes, resulting in an efficiency increased of ~65%.  This week’s installment of efficiency improvements boasts similar figures, but through the replacement of misused liquid nozzles rather than open pipe.

The image above shows a compressed air manifold with a number of nozzles.  BUT, the nozzles in this manifold are not compressed air nozzles, nor do they have any engineering for the maximization of compressed air consumption.  These are liquid nozzles, usually used for water rinsing.

In this application, the need was to blow off parts as they exit a shot blasting machine.  When the parts exit the shot blasting process they are covered in a light dust and the dust needs to be blown away.  So, the technicians on site constructed the manifold, finding the liquid nozzles on hand during the process.  They installed these nozzles, ramped up the system pressure to maintain adequate blow off, and considered it finished.

And, it was.  At least until one of our distributors was walking through the plant and noticed the setup.  They asked about compressed air consumption and confirmed the flow rate of 550 m³/hr. (~324 SCFM) at 5 BARG (~73 PSIG).

The end user was happy with the performance, but mentioned difficulty keeping the system pressure maintained when these nozzles were turned on.  So, our distributor helped them implement a solution of 1101SS Super Air Nozzles to replace these inappropriately installed liquid nozzles.

By implementing this solution, performance was maintained and system pressure was stabilized.  The system stabilization was achieved through a 61% reduction in compressed air consumption, which lessened the load on the compressed air system and allowed all components to operate at constant pressure.  Calculations for this solution are shown below.

Existing compressed air consumption:  550 m³/hr. (324 SCFM) @ 6 BARG (87 PSIG)

Compressed air consumption of (9) model 1101SS @ 5.5 BARG (80 PSIG):  214 m³/hr. (126 SCFM)

Total compressed air consumption of 1101SS Super Air Nozzles:

Air consumption of 1101SS nozzles compared to previous nozzles:

Engineered air nozzles saved this customer 61% of their compressed air, stabilized system pressure, improved performance of other devices tied to the compressed air system, and maintained the needed performance of the previous solution.  If you have a similar application or would like to know more about engineered compressed air solutions, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Increasing Efficiency With EXAIR Super Air Nozzles

Earlier this morning I received a phone call from a gentleman in search of a more efficient compressed air solution.  The application was to remove thermoformed plastics from a mold immediately after the mold separates.  In the current state, the application is consuming ~40% of the available compressed air in the facility through the use of (9) ¼” open pipes, consuming a confirmed 288 SCFM at 60 PSIG.  Due to the use of an open pipe, this customer was facing a safety and noise concern through the existing solution.

After discussing the application need and the desire to reduce compressed air use, reduce noise, and add safety, we found a suitable solution in the 1101 Super Air NozzleInstalling (9) of these EXAIR nozzles will reduce the compressed air consumption by over 65%!!!  Calculations for this savings are below.

Existing compressed air consumption:  288 SCFM @ 60 PSIG

Compressed air consumption of model 1101 @ 60 PSIG:  11 SCFM

Total compressed air consumption of  (9) 1101 nozzles:

Air savings:

This is the percentage of air which the new EXAIR solution will consume.  To put it another way, for every 100 SCFM the current solution consumes, the EXAIR solution will only require 34.38 SCFM. Installing these EXAIR nozzles will result in lower operational cost, lower noise levels, and increased safety for this customer – all while maintaining or improving the performance of the blow off solution in this application.

EXAIR Application Engineers are well versed in maximizing efficiency of compressed air systems and blow off needs.  If you have an application with a similar need, contact an EXAIR Application Engineer.  We’ll be happy to help.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

Removing Static From Diaper Absorbent Material

This is where the absorbent material inside a disposable diaper is made

The image above shows one step in the process of disposable diaper manufacturing.  In this step of the process, the absorbent material is ground through a mill on the top of the “bunker” where it falls down a shaft and onto a mesh screen.  Once on the mesh screen, the material is repressed into the proper size and shape for placing into the diapers.

This manufacturer contacted one of our Russian distributors about the application because the milling of the absorbent material was creating static.  This static caused the material to adhere to the walls of the bunker chute and to unevenly distribute onto the mesh.  This unevenness leads to holes in the pressed/shaped absorbent material which translates to a reject rate of ~1 out of every 20 diapers.

An EXAIR Ion Bar

The ideal solution in this case needed to eliminate the static within the chute to allow for proper distribution on the mesh below and proper material placement into the diapers.  An Ion Bar was originally desired by the customer, but material accumulation on the emitter points was a concern so this solution was removed from consideration.

An EXAIR Ion Air Cannon

An Ion Air Cannon, however, was able to provide the desired solution by mounting outside of the chute and feeding a low volume of ionized air to remove the static.  The ionized airflow from the Ion Air Cannon is strong enough to permeate the full volume of the application, but low enough to not disturb the absorbent material within the process. Using an Ion Air Cannon allowed this manufacturer to eliminate defects and wasted materials, increase their throughput, and improve the quality of their products.  Defects dropped from 1/20 diapers to less than 1/1000.

If you have a similar application or similar needs, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

316 Stainless Steel Line Vac Conveys Cookies in Creamery

Cookies in need of pneumatic conveyance at creamery

An overseas ice cream manufacturer reached out to me recently with a request for assistance.  They were in search of a better means to transfer “inclusions” from a storage bin into the blending tanks of their creamery.  The “inclusions” in question, shown above, looked familiar.  I’ve found identical cookies stashed in my sons’ favorite places around the house, so I’m somewhat familiar with their transfer from one place to another.  Fortunately, in this application the cookie transfer is deliberate whereas it is always “magic” or “no one knows how it got there” when it happens at home.

Both solid cookies and crumbs (shown above) are conveyed.

Seeing as how this application involves the transfer of foodstuffs, we immediately explored a 316 grade stainless steel solution, and gathered the necessary data for determining the proper pneumatic conveyor (an EXAIR Line Vac).  Our Line Vacs utilize a high velocity airstream which travels along the ID of a conveyance tube to move material.  Because of this, application specifics like material/material size, bulk density, conveyance height and distance, and required conveyance rate play a key role in proper sizing.  Here’s how the specifics looked for this application:

 

Material:  Dry cookies and cookie crumbs, 8mm-50mm in diameter (5/16” – 2” in diameter)

Bulk density:  0.69 g/cm³ (43 lb./ft.³)

Conveyance height:  None

Conveyance distance:  5m (16.5 feet)

Required conveyance rate:  As high as possible, preferably in the range of 500kg/hr. (1100 lb./hr.)

Available compressed air supply:  170m³/hr. @ 5.5 BARG (100 SCFM @ 80 PSIG)

Material constraints:  316SS mandatory

 

With these details well defined, I used our empirical test data to appropriately size a suitable Line Vac.  In this case, we had a viable solution in our Heavy Duty Line Vac with regards to conveyance rate, but this solution is not the proper material.  So, we matched performance of a Heavy Duty Line Vac in our 316SS Line Vac using model HP6064-316.  Model HP6064-316 is not a stock option and not shown on the website, so having a proper dialogue with an Application Engineer was critical to dialing in on the right solution for this application.

Once the solution was confirmed, this customer was all set.  We worked with them on every aspect of the application solution and ended up shipping them (3) specialized Line Vacs in 316 stainless steel.  The Line Vacs are up and running, helping to make delicious ice cream for expecting customers.

If you have a similar application or are interested in exploring a Line Vac solution, now is the time to act.  We have a Line Vac promotion running through the end of October that includes a free 2” Flat Super Air Nozzle with the purchase of any Line Vac.  Application Engineers are available for any questions you may have via phone (1-800-903-9247), email (techelp@exair.com), and online chat.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

EXAIR Line Vac Promotion Thru October 2017!

EXAIR will be giving away a free 2” Super Air Nozzle with the purchase of any EXAIR Line Vac from September 1st through October 31st, 2017.  This special promotion will apply to all versions of Line Vac orders, whether aluminum, stainless steel, heavy duty, threaded/non-threaded, or 316SS sanitary flanged.  Order within the promotional period and receive the free model 1122, a value of $65.00! The 2″ Flat Super Air Nozzle is more durable than plastic flat nozzles, operates at lower noise levels and produces a powerful blast of compressed air in a laminar sheet.

EXAIR’s Line Vac family

Line Vacs provide a fast, easy way to pneumatically transfer dry materials from one location to another.  They eliminate the need to have personnel manually transferring materials via bag, super sac, or bucket-and-ladder setups.  Doing so reduces worker fatigue and allows conveyance to occur simultaneously with other process operations.

Line Vac removing trimmed scrap from label making application

What kind of an impact can this have?  Here’s a link to a recent blog post where an EXAIR Line Vac saved the end user from having to shut down their conveyor to allow cleaning of spilled material underneath.  And here’s a link to an application using Line Vacs to empty and refill a large tank full of desiccant.  And here’s a link to an application where we customized a Line Vac for conveyance of dog bedding material.  You get the idea…

Depending on application parameters such as bulk density of the material (lbs/ft³ or kg/m³), conveyance height/distance, and required conveyance rate, we can size a Line Vac properly through the support of our Application Engineers who have years of experience working with these products and their implementation into industrial solutions.

The EXAIR Line Vac Promotion – now through October 31st

We’re here to help you find a pneumatic conveyance solution for your application, and earn a free nozzle in the process.  Contact our Application Engineers for assistance today.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE

EXAIR Provides Same Day Solutions For Customers In Need

Solving customer problems by shipping product the same day is a common occurrence at EXAIR. Here is another example.

 

EXAIR Cabinet Cooler installed on a control panel in a distribution center for hygienic products.

As companies grow and add more personnel, the details of projects and solutions can get lost if not recorded well.  Newer employees may not have knowledge of solution specifics, and unknown details can be hard to discover, especially in larger organizations.  An example of this happened recently when one of our customers contacted me about the Cabinet Cooler shown in the image above.

The NEMA 12 Cabinet Cooler was working flawlessly and had been for some time.  As temperatures rose, however, other machines in this facility began to experience overheating conditions leading to machine downtime, decreased throughput, and increased stress on operations personnel.

One of the maintenance workers noticed that the cabinet with the EXAIR Cabinet Cooler was functioning properly, so they did a quick Google search of the product.  They were met with numerous postings about the theory of operation for Cabinet Coolers and Vortex Tubes, how-to videos for installation/thermostats/side mount kits, and our blog site with countless application solutions provided by our products.

Figuring they’d found the right place, they reached out to me via email and shared their story.  And, what they ultimately needed from me was help identifying which Cabinet Coolers they had on hand to mimic the solution in other, identical machines.

Another angle of the Cabinet Cooler in this application.

Thankfully they provided the image above, which shows a label near the compressed air inlet designating the compressed air consumption (at 100 PSIG).  (See below)

The critical piece of information we needed to determine the model number of this Cabinet Cooler (in the red circle).

Based on this label and the dimensions of the Cabinet Cooler, I was able to identify this as our model 4025 NEMA 12 Cabinet Cooler, which is part of the larger, complete system model 4325.  After providing the model number, price, and availability, this customer was able to order the needed Cabinet Coolers which were shipped the same day.

Shipping solutions from stock is an everyday thing here at EXAIR.  If you’re in need of a solution for cooling, cleaning, conveying, removing static, or coating contact an EXAIR Application Engineer.  We can help you solve your problem – TODAY!

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE