Do I Have To Install A Compressed Air Filter?

2″ Heavy Duty Line Vac Kit – Model 152200

Recently I took a call from an existing customer that is questioning their Heavy Duty Line Vac Kit setup. They are experiencing around a 38 psig pressure drop from before the filter in the system to the inlet of the Line Vac.  At first glance, they assumed this was due to the filter restricting the flow. They then posed the question, “Do I have to run this filter or can I take it out?  I mean I already have a filter at my compressor.” The answer is yes, install the filter. It will keep dirt, scale and condensate from entering the Line Vac or other components downstream. In the case of a Line Vac, a filter will also prevent this unwanted debris from getting into the material being conveyed.

Example of an Improper Filter Setup

However, this is a great question, especially when assuming the filter is causing the pressure drop – but that was not the case for this application.  So more questions were asked to our customer to determine what the root cause of the pressure drop could be. Seeing a pressure drop across a filter can be caused by several factors.

One would be an inappropriately sized filter. This can restrict the volumetric flow of air through to the point of use causing a pressure drop.  All of the filters supplied with our product kits are auto-drain, have 5 micron filter elements and appropriately sized to operate the product at 80 psig inlet pressure so this was not the problem.

The next issue could be that the filter is clogged, this brought on another question.  If you see more than a 5 psig pressure drop across a filter from EXAIR then we suggest changing out the filter element as it could be clogged and not permitting the full volumetric flow through.  This installation was fairly new and a quick test without a filter element installed proved it was not the filter element that was clogged.

That brought us to the last variable, the length, size, and number/type of fittings between the filter and the Heavy Duty Line Vac. This length of pipe was more than 30′ in length and was only appropriately sized for a 10′ length or shorter run.  The customer was using a 1/2″ Schedule 40 black iron pipe to feed a 2″ Heavy Duty Line Vac at 80 psig inlet pressure. The 2″ Heavy Duty Line Vac Kit will utilize 75 SCFM at 80 psig inlet pressure.  That will need a 1/2″ Sched. 40 pipe that is 10′ long or less in order to not have friction loss within the feed pipe.  Armed with this information the customer is researching whether or not the line needs to stay that long.  If it does, they will have to re-plumb the system with a minimum of a 3/4″ Sched. 40 black iron pipe.

Luckily this was all able to be discussed within a few hours of time and the customer is on their way to an optimal supply system for their in-line conveyor.  One brief phone call took this customer from lackluster performance and thinking a product was not going to work for what they need, to performing beyond their expectations, and being able to keep up with their production needs.

If you have a product or any part of your compressed air system that you question why it may be performing or not performing a certain way, please do not hesitate to reach out to our knowledgeable team of Application Engineers. We are always interested in finding a solution to your needs.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

Contaminated Air Supply Leads To Unwanted Results

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Rust from the air supply found inside a compressed a Reversible Drum Vac.

One of the greatest attributes of EXAIR products is their ability to stay in operation for years on end without any maintenance.  With no moving parts to wear out, there really is little-to-no upkeep required.  So, when we receive notice from a customer that an EXAIR product is not working properly, we most always seek to establish the pressure, volume, and quality of the compressed air supply.  By examining these three variables, we can usually pinpoint the source of the performance discrepancy.

I had an exercise in this routine a few days ago with a Reversible Drum Vac (RDV).  The RDV had arrived at EXAIR after the customer noticed a drop in performance.  The RDV went from operating normally to gradually loosing strong vacuum when vacuuming liquids out of a coolant sump.

The end user and I discussed the air supply pressure, line size, and available volume of compressed air to operate the RDV which all seemed to be in order.  Compressed air supply pressure was 80 PSIG, they were using the EXAIR supplied (properly sized for the product) compressed air hose, and the unit had functioned in this exact setup for some time, so we were confident in the ability of the compressed air system to supply adequate volume.

In most cases, when an RDV gradually loses vacuum, or experiences a change in performance without a change in application parameters, contaminants from the compressed air system can be found inside of the RDV.  And, that is exactly what happened here.

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Reversible Drum Vac “plug” – notice the rust on the everything below the O-ring (everything in contact with the compressed air supply)

I first tested the RDV for vacuum level and flow, both of which were low.  When I disassembled the RDV I noticed what looked like rust on all surfaces which are in contact with the compressed air stream (photo above).

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Internals of the Reversible Drum Vac “body”; littered with rust

Then, I peered into the body of the drum vac and saw the root of the problem – dirt and rust from the compressed air system had accumulated within the RDV, restricting compressed air flow and causing the decay in performance.

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Rust and shim as they were dumped out of the Reversible Drum Vac body
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Another photo of the rust

After a quick cleaning of the RDV, performance was perfect and the RDV was ready to go back into operation.  The end user and I discussed my findings along with proper air filtration to prevent a similar occurrence in the future.  They were glad to know their RDV was in working order, and we were both glad to confirm the root cause.  With a new filter separator installed at the compressed air line feeding this RDV, trouble-free and maintenance-free performance can be expected for a long time to come.

If you have a similar application need, or think an EXAIR solution may benefit your process, contact an EXAIR Application Engineer.

Lee Evans
Application Engineer
LeeEvans@EXAIR.com
@EXAIR_LE