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We are committed to providing excellent technical support
for our current and potential customers.

Our Technical Service Staff is well-trained on pneumatic applications and are available to discuss application issues regarding Wilkerson products. We encourage you to view our Installation and Maintenance sheets and contact either your nearest Wilkerson distributor or Technical Service Staff for additional help. The Frequently Asked Question section of this site serves to address many of the typical questions that our Technical Service Staff receive.

If your question is not answered here, please send e-mail to our Applications Engineering Specialist or fax your question to (269) 629-2475.


FREQUENTLY ASKED QUESTIONS - FRL 

  1. Can someone change from a manual to an auto drain on an 18/28 series filter in the field?

  2. How do I properly size and determine feasible application of a filter, regulator or lubricator?

  3. When should I use an AtoMist® lubricator instead of an EconOmist® lubricator?

  4. What is the difference between a relieving and a non-relieving regulator?

  5. When do the DP indicators that come standard with Wilkerson coalescing filters turn from green to red?

  6. How can I find the part number for the correct replacement element for my Wilkerson filter?

  7. How do I know which filter Replacement Element Kit to order?



FREQUENTLY ASKED QUESTIONS - AIR DRYERS 

  1. How much water is in compressed air?

  2. How much water can be removed by drying compressed air?

  3. What’s the best type of dryer?

  4. What type of filters are recommended for dryers?

  5. I have a refrigerated air dryer installed and it had been working fine, but suddenly I’m finding water in my compressed air, what's going on?

  6. How do I write a specification to ensure I get the air dryer features I need?


  

Wilkerson
Pneumatic Division  v  Richland, Michigan 49083 USA
Phone:  269.629.2550 
Fax:  269.629.2475

Wilkerson European Service Centre

Walkmill Lane, Bridgtown  v  Cannock, Staffs WS11 0LR

United Kingdom

Tele No. 0044 (0) 1543 456000

Fax No. 0044 (0) 1543 456170

© Wilkerson  All Rights Reserved.


 

FRL ANSWERS --

Answer 1: Yes. The manual drain can be removed by loosening the drain knob all the way until the stem slips. Then remove the drain knob by squeezing it with a pair of pliers and turning it in a plane parallel to the direction of flow through the unit. The knob and stem can then be easily removed. The auto drain may be installed by putting the drain stem through the hole in the bowl and tightening the nut onto stem from the other side.
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Answer 2: Basic information one should know is pipe size, inlet pressure (PSIG), flow (SCFM) and for regulators, the regulated pressure range. The temperature of the air stream and the ambient temperature, and whether or not any incompatible chemicals, solvents, vapors, or oils are present in the atmosphere or air stream is also important. One can estimate flow by adding the usage of all the machinery being supplied downstream (point of use). It is always good to be a little conservative, and add flow for users who might occasionally blow down equipment, or otherwise exhaust air for some reason. You can also size Wilkerson products by using the performance charts that are in each product section of our catalog 9EM-TK-190 (8/2003). It is always good design to have no more than a 2-3 PSI pressure drop, at maximum rated flow, with a clean element. Oversizing filters costs you a little extra in purchase price; undersizing filters costs you in wasted energy (high pressure drop) over the entire life of the filter in the system!
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Answer 3: The AtoMist® sends finer oil aerosol particles downstream than does the EconOmist® lubricator. These oil particles will stay suspended in the airstream much longer than the larger economist droplets. Therefore, it is better to use the AtoMist® when the lubricator cannot be placed within about 10-12 feet of the application, or if the air flow in your system is intermittent. The ratio of drops of oil in an EconOmist® is 1:1; that is, for every drop you see in the sight adjustment dome, you get one drop of atomized oil in the air stream. For the AtoMist®, the ratio is 33:1. A good starting point for lubrication is about one drop of oil for every twenty cubic feet of air flow.
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Answer 4: A relieving regulator will exhaust downstream air when the secondary pressure rises above the set pressure of the regulator. This could happen from some piece of machinery inducing a back pressure in the system or from merely turning down the pressure of the regulator (regulator will relieve while adjusting to a lower pressure). A non-relieving regulator will not exhaust downstream air regardless of secondary pressure.
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Answer 5: The DP indicators measure the outlet pressure from the filter to the inlet pressure. A spring will move the green portion of the indicator to red when the differential pressure between inlet and outlet reaches 7 PSI. This differential indicates that it is time to replace the element.
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Answer 6: By going to the page in our product catalog 9EM-TK-190 (8/2003) where the filter is shown. On the page with the performance charts, you will find replacement element kits listed. You can also find this information listed on the Installation and Maintenance Sheet for your filter. And, refer to the chart following the next question.

AIR DRYER ANSWERS --

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Answer 1: For example, a 25 HP Air Compressor running continuously for 24 hours at full load, with inlet conditions of 75° and 75% relative humidity, can generate up to 18 gallons per day. There will be proportionately more or less water depending on the compressor size, inlet conditions and duty cycle.
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Answer 2: Actually, nearly two-thirds of the water in compressed air (or 12 of 18 gallons in the answer to question one can be removed with an efficient and clean aftercooler. An aftercooler is a heat exchanger located at or downstream of the air compressor which is either cooled by a fan or can be water cooled. By reducing the compressed air temperature every twenty degrees, half of the water vapor is condensed to a liquid and can be removed with a moisture separator and automatic drain trap. Most aftercoolers reduce the temperature to about 100°F.

However, this is still not "dry enough" for many uses of compressed air, such as painting, instrumentation, robotics, etc.

The next step in drying is to install a refrigerated air dryer. This continues to cool the air to just under 40°F., which reduces the water left to only 5 % of the total (using the example in question one, of the 18 gallons per day total, less than one gallon of water is left). This is adequate drying for 90% of the compressed air systems.

If the compressed air lines are not exposed to temperatures below 40°F. then the remaining water will stay in a vapor or gas form and will not condense or liquefy.

If there are air lines exposed to freezing temperatures or additional dryness is required due to the critical use of the compressed air, then a desiccant dryer would be required. Desiccant dryers remove over 99% of the water in compressed air and are usually rated with pressure dew points of minus 40 or minus 100°F.

A membrane dryer could also be used downstream of a refrigerated dryer for point-of-use/ critical applications.

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Answer 3: It depends. A desiccant dryer provides more efficient water removal, but it's also more expensive initially and most require about 15% of the rated inlet capacity (SCFM) for purging, so you lose compressed air.

Therefore, the "best" type of dryer in many cases is a refrigerated dryer due to its lower initial and operating cost.

Many newer compressed air systems may use a combination of dryers. A refrigerated dryer sized for the air compressor will remove 95% of the water and provide adequate dry air for most plant applications. Additional desiccant or membrane dryers sized for the specific application (i.e. dust collector exposed freezing temperature; CNC plastic molding equipment; food processing application, etc.) can be installed downstream of the refrigerated dryer and prior to where the critical dry air is required.

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Answer 4: We recommend a 5-micron pre-filter for a refrigerated dryer. This removes the larger particles and droplets and helps keep the internal heat exchanger on the dryer cleaner. A high efficiency coalescing filter rated at .01 microns can be placed downstream of the refrigerated dryer for additional cleaning.

On a desiccant air dryer we recommend the 5 micron pre-filter followed immediately by the coalescing .01 micron filter. This helps prevent any oil contamination of the desiccant material. A 1 micron particulate filter should be placed downstream of the desiccant dryer to capture any desiccant dust from migrating downstream.

A vapor filter which removes oil vapor, odors and taste can be used as a final filter in either case.

In all filter selections, the rated pressure drop should be as low as possible (1-3 PSI) to ensure longer element life.

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Answer 5: There could be several explanations for this problem. The most common is the auto drain on the moisture separator of the dryer is fouled up and not working. "Float-type" drain traps require regular maintenance. To help eliminate this problem, we recommend electric solenoid valve drain traps.

Other maintenance-related reasons could be excessive high inlet temperature, high ambient temperature, a dirty condenser, heat exchanger, or a malfunctioning fan motor.

The most serious explanation could be a leak in the refrigerant system or a bad refrigeration air compressor.

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Answer 6: Contact Wilkerson Support at (269) 629-2550 or fax (269) 629-2475 for specification assistance and application engineering.
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If your question was not answered here, please send e-mail to our Applications Engineering Specialist and they will respond.