REMOVE THE WATER AND MOISTURE
from your Compressed Air System
TO IMPROVE YOUR COMPRESSED AIR QUALITY & EFFICIENCY

Q. Do you have Water in Your compressed air? 
                  
A. YES 

Q. How does Water get in your compressed air? 
 
A. Compressor inlet

 Water vapor (humidity-moisture) enters the air system through the air compressor inlet air filter. The air compressor sucks in approximately 7 cubic feet of atmospheric air at 0 psig, and that volume of air is compressed into 1 cubic feet of air at 100 psig. The water vapor (humidity-moisture) that was in the 7 cubic feet of atmospheric air is now compressed into 1 cubic feet of compressed air. 

There are 3 forms of water in compressed air:

• Liquid water
• Aerosol (mist)
• Vapor (gas) 
  
  Liquid water is easily removed by air-water separators. They remove 99% of the liquid water and 0% water vapor. 
  
  Water in Aerosol or Vapor form is more difficult to remove and requires the use of a Compressed Air Dryer. 
  
  For every 50°F drop in compressed air temperature, the moisture holding capacity of air is reduced by 50%. Drying prevents liquid water forming downstream where it can contaminate or damage the system causing operating problems, costly maintenance, and repairs.
  

Q. How do you select the Compressed Air Dryer you need for your equipment application?

A. The KEY to selecting the correct COMPRESSED AIR DRYER is to know the DEW POINT suitable for your equipment's application.

Q.  What is "DEW POINT"?

A. The measurement of air dryness is dew point.  

Dew point is the temperature below which water vapor will condense to liquid water at given conditions. Lowering the dew point effectively means the system can endure much lower temperatures before water droplets begin to condense.  

Q. How do you determine the dew point suitable for your application when selecting a compressed air dryer?

A. The best and easiest way is to ask the Manufacturer what the pressure dew point (PDP)requirements are for your equipment.

Another method is to calculate the dew point temperature.


Q. How do you CALCULATE DEW POINT TEMPERATURE ?

A.  To calculate your DEW POINT TEMPERATURE...

1. Determine the lowest ambient temperature your compressed air piping system will be exposed to. Check the location of air lines throughout air conditioned or unheated areas underground or between buildings.
(For example, your compressor and piping is inside your facility and the lowest air temperature it would ever be exposed to is 58ºF.)

DRY YOUR COMPRESSED AIR USING 
REFRIGERATED AIR DRYERS

HOW A REFRIGERATED AIR DRYER WORKS

• The refrigerated air dryer cools the incoming compressed air first in an air-to-air heat exchanger where the outgoing cool dry air pre-cools the hot incoming air and condenses some moisture out.
  
• Then the incoming air enters an air-to-refrigerant heat exchanger where the air is cooled to 38º F by the liquid refrigerant. This process causes the moisture to condense into liquid water and it is drained away. The out going air then enters the air-to-air heat exchanger and is warmed up to keep the outside of pipes from sweating.
  
• The refrigeration compressor pumps hot hi-pressure gas refrigerant (Freon) into the condenser which transfers the heat from the refrigerant gas to the ambient air as the gas condenses into a liquid.
  
• The liquid refrigerant (Freon) is then metered to a cold low pressure where it enters the air-to-refrigerant heat exchanger and the heat from the hot compressed air is adsorbed into the cold refrigerant (Freon).
  
• The refrigeration compressor then sucks low pressure hot gas refrigerant (Freon) into the refrigeration compressor and the cycle starts over again.
  

• Dew Point Temperature Along with Incoming Compressed Air Temperature
  Help Determine which Series of Arrow Refrigerated Air Dryer you need.

  
  

  Click here to choose a standard series refrigerated air dryer if your incoming compressed air temperature is 100º F or less and you need a Pressure Dew Point  (PDP) of +35º F or +50º F.

  
  

  Click here to choose a hi-temp series refrigerated air dryer if your incoming compressed air temperature is over 100º F and you need a Pressure Dew Point of +35º F.

  
  

  Click here to choose a hi-temp 50 series refrigerated air dryer if your incoming compressed air temperature is over 100º F and you need a Pressure Dew Point of +50º F.

  
  

  After selecting the series of dryer required, determine the actual conditions under which the dryer will be operating. This allows you to determine the correct size of the dryer.

  
   

FACTORS TO CONSIDER WHEN DETERMINING THE SIZE
OF A REFRIGERATED COMPRESSED AIR DRYER

• Pressure Dew Point needed (PDP)
• Volume of compressed air (SCFM)
• Maximum compressed air inlet temperature (°F)
• Maximum ambient temperature (°F)
• Minimum ambient  temperature (°F) 
• Maximum compressed air pressure (PSIG)
• Maximum allowable pressure drop (PSIG)
  
  Note: Any deviation from standard conditions requires air dryer size adjustments.  Use Correction Factor Tables to help determine dryer size.
  
   

  __________________________CORRECTION FACTOR TABLES_____________________________
  
  See the following tables for Correction Factors for
  STANDARD REFRIGERATED AIR DRYERS:

  Standard Rated Conditions Are: 

  • (100º F Inlet Air Temperature)
  • (100º F Ambient Temperature)     
  • (100º Psig Inlet Pressure)  
  • (38º F Dew Point Temperature)  

  Correction Factors (Multipliers) to Adjust Dryer Flow Capacity Other Than Standard Rated Conditions Are:

  TABLE 1 –Correction Factors (Multipliers) for Inlet Air Temperature and Pressure
  
  

  INLET TEMPERATURE
  INLET Pressure (PSIG)	80ºF	90ºF	100ºF	110ºF	120ºF
  50	1.35	1.05	0.84	0.69	0.56
  80	1.50	1.17	0.95	0.79	0.66
  100	1.55	1.23	1.00	0.82	0.70
  125	1.63	1.31	1.07	0.91	0.74
  150	1.70	1.37	1.13	0.95	0.80
  175	1.75	1.42	1.18	0.99	0.84
  200	1.80	1.47	1.22	1.03	0.89

     
  
  TABLE 2 – Correction Factors for Ambient Temperature  
  
  

  AMBIENT TEMPERATURE	80ºF	90ºF	100ºF	110ºF
  Multiplier	1.12	1.06	1.00	0.94

     
  
  TABLE 2 – Correction Factors for Dew Point Temperature 
   
  

  DEW POINT TEMPERATURE	38ºF	40ºF	45ºF	50ºF
  Multiplier	1.0	1.1	1.2	1.3

  
  
  To size dryer capacity for conditions other than the Standard Rated Conditions, use the Correction Factors (Multipliers) from Table 1, 2 and 3.
  
  Example: You've determined you need to treat 500 CFM of Compressed Air for your business. You are considering the Model F-500 (which treats up to 500 CFM). But you need your dryer to run under the following conditions - different from the Standard Rated Conditions (which may include higher temperatures due to hot days of summer):
  

• 120º F Inlet Air Temperature  (Standard =100º F Inlet Air Temperature)

• 125 Psig Inlet Air Pressure (Standard =100º Psig Inlet Pressure) 

• 110º F Ambient Air Temperature (Standard =100º F Ambient Temperature) 

• 38º F Dew Point Temperature  (Standard =38º F Dew Point Temperature)  
  
  The Model F-500 can treat up to 500 CFM of compressed air under Standard Rated Conditions (listed above).  When conditions change, like surrounding temperatures on hot summer days, these conditions affect how much compressed air your dryer can treat (it could be more or less CFM).  If conditions vary from Standard Rated Conditions , then your air dryer may not perfomance standards. Use the tables shown to determine the correct size of dryer you need under your specific conditions.
  
  Look @ Table 1
  Find Where Inlet (125 Psig) Pressure & Inlet Temperature (120º F) Intersect.
  This number is Your Correction Factor (.74) Multiplier.  
  Multiply (500) X (.74) = 370 CFM Corrected. 
  You can find the CFM of a dryer on this web site listed on the dryer's product page.  Click here to see details for Model F-500.
  
  Look @ Table 2
  Determine the Maximum Ambient Temperature surrounding the Dryer. For our example, we will use 110ºF (for hot summer day). 
  The table tells you your Correction Factor is (.94)
  Use the corrected CFM number determined by Table 1 (370) and multiply it by the Table 2 correction factor for 110º F(.94).
  Dryer Corrected CFM (370) X (.94) =348 CFM Corrected.
  
  Look @ Table 3
  What dew point do you need to prevent water from forming down stream in your piping? (38º F)
  The Dryer Correction Factor for  38ºF is 1.  Multiply that time the Dyer Corrected CFM determined from Table 2.
  (1) X 348 CFM = 348 CFM Corrected
  
  
  USING THE ABOVE TABLES, we can conclude that a 500 CFM Dryer working under these NON-Standard conditions is only able to treat 348 CFM and is too small for our needs.
  
  
  The following are tables for HIGH TEMPERATURE AIR DRYERS only:

•  See the following table for Corrected Flow Capacities for
  HI-TEMPERATURE REFRIGERATED AIR DRYERS:

  Flow Capacity CFM @ 160°F /  35°F Pressure Dew Point
  Model	100 PSIG	140 PSIG	175 PSIG
  F-3528	21	21.9	24
  F-3529	30	36.8	40
  F-3530	50	56	64
  F-3531	70	81	88
  F-3532	105	130	140

   

  Flow Capacity CFM @ 140°F  /   35°F Pressure Dew Point
  Model	100 PSIG	140 PSIG	175 PSIG
  F-3528	24	27	29
  F-3529	44	49	53
  F-3530	70	78	83
  F-3531	85	95	102
  F-3532	148	167	178

   

  Flow Capacity CFM @ 120°F  /   35°F Pressure Dew Point
  Model	100 PSIG	140 PSIG	175 PSIG
  F-3528	34	37	39
  F-3529	50	58	64
  F-3530	70	81	90
  F-3531	100	115	128
  F-3532	210	229	240

    See the following table for Corrected Flow Capacities for
  50 SERIES HI-TEMPERATURE REFRIGERATED AIR DRYERS:
  

  Flow Capacity CFM @ 160°F  /  50°F Pressure Dew Point
  Model	100 PSIG	140 PSIG	175 PSIG
  F-5028	21	23	25
  F-5029	30	33	36
  F-5030	50	54	58
  F-5031	70	73	78

   

  Flow Capacity CFM @ 140°F   /   50°F Pressure Dew Point
  Model	100 PSIG	140 PSIG	175 PSIG
  F-5028	27	31	34
  F-5029	34	38	41
  F-5030	63	71	76
  F-5031	81	91	98

   

  Flow Capacity CFM @ 120°F  /   50°F Pressure Dew Point
  Model	100 PSIG	140 PSIG	175 PSIG
  F-5028	34	37	40
  F-5029	41	45	49
  F-5030	70	77	85
  F-5031	120	132	139

   
  
  Correct Dryer size is most important for trouble free performance
  _____________________________________________________________________________________________________________________
  
  
  SIMPLE TROUBLESHOOTING

  Types of problems that can affect equipment performance, and hence energy consumption include:
  
  ● high compressor delivery temperatures-High-Temperature Dryer is recommended
  
  ● internal contamination effects dew point - pre-filtration is recommended
  
  ● high ambient temperatures- ventilation
  
  ● faulty drain allowing liquids downstream of the dryer-repair drain
  
  ● loss of refrigerant -repair, evacuate and charge.