Great Lakes Air Products GPS-500 User manual

Great Lakes Air Products
1515 S. Newburgh Road
Westland, MI 48186
PH: 734-326-7080
www.glair.com
COMPRESSED AIR DRYER
INSTRUCTION MANUAL
GPS-SERIES
HEATLESS
REGENERATIVE
DESICCANT DRYERS
Contents
Introduction
2
General Safety Information
2
Proper use of Dryer
3
Receiving Equipment
3
Installation Location
3
Inlet Conditions
3
Pre-Filtration
4
Condensate Drains
4
After-Filtration
4
Block & Bypass
4
Optional Backpressure Regulator
5
Purge Exhaust Piping
5
Electrical Connection
5
Desiccant Loading Procedure
5
Operation
6
Dewpoint Demand Controller
7
Start Up
7
Sequence Controller
8
Maintenance
9
Troubleshooting Guide
Quick Reference
10
Troubleshooting Tutorial
10-13
Warranty
14

GPS Heatless Regenerative
Page 2 of 14
INTRODUCTION
Before attempting any installation or maintenance on the dryer, please
carefully read this entire manual.
Great Lakes Air Products genuine parts, manufactured to design tolerances, are developed for optimum
dependability –specifically for Great Lakes Air Products dryer systems. Design and material innovations
are the result of years of experience with hundreds of different compressor and dryer applications.
Reliability in materials and quality assurance are incorporated in our genuine replacement parts.
Your authorized Great Lakes Air Products Dryer distributor offers all the backup and reassurance you’ll
need. Our network of authorized distributors provides the finest product support in the air compressor
industry.
Your authorized distributor can support your Great Lakes Air Products Dryer with these services:
1. Trained parts specialists to assist you in selecting the correct replacement parts.
2. Repair and maintenance kits designed with the necessary parts to simplify servicing
your dryer.
3. Authorized distributor service technicians are factory trained and skilled in compressor and
dryer maintenance and repair. They are ready to respond and assist you by providing fast,
expert maintenance and repair services.
To Contact Great Lakes Air Products or locate your local distributor:
Visit: www.glair.com or
Call: [phone]
Failure to install the compressed air dryer per this manual or any change to the dryer not previously
authorized by the manufacturer will void the warranty.
The information and specifications in this manual are in accordance with the information in effect at the
time of printing. The manufacturer reserves the right to make changes without notice or incurring
obligation.
GENERAL SAFETY INFORMATION
General Warning
The associated text outlines conditions which could indicate a hazardous situation that
has some probability of death or severe injury. It could also represent the possibility of
damage to the associated equipment.
Electrical Hazard
The associated text outlines conditions which could indicate a hazardous situation that
has some probability of death or severe injury.
Only qualified personnel can use and service electrically powered devices. Be sure that
the voltage is disconnected before any work is performed.
Danger Hazard
Compressed air is a highly hazardous energy source. Depressurize the system prior to
performing any work or maintenance on that system. Never work on equipment with
parts under pressure.
Breathing Air
Air treated by this equipment may not be suitable for breathing without further
purification. Refer to applicable standards and specifications for the requirements of
breathing quality air.

GPS Heatless Regenerative
Page 3 of 14
PROPER USE OF DRYER
This dryer has been designed, manufactured, and tested to separate humidity normally contained in
compressed air only. Any other unauthorized use will be considered improper. The manufacturer will
void the warranty and not be held responsible for any problem arising from improper use. The correct
use requires adherence to installation conditions specified in this manual.
RECEIVING EQUIPMENT
Immediately upon receipt of equipment, remove all crating and packaging around equipment. Examine
machinery for any damages either external or internal that may have occurred in transit.
If there is any physical damage note it on the bill of lading during delivery. If damage is detected after
the equipment delivery; contact the local terminal to report all damages and file a claim immediately with
the transportation company. The carrier is legally responsible for any damages, since the unit is shipped
F.O.B.
This dryer is supplied tested and assembled however some components on larger units have been
removed and attached to the skid independently, to avoid any damage during shipping. On models
GPS-500 and larger the desiccant material is shipped on a separate skid from the dryer for installation
instructions see DESICCANT LOADING PROCEDURES
The only operation left to the user is the connection to the plant in compliance with the instructions given
in the following chapters.
INSTALLATION LOCATION
Particular care is required in selecting the installation site, as an unsuitable location could
jeopardize the proper operation of the dryer. This unit is not suitable to be used in an
explosive atmosphere, or where the risk of fire could be present.
The unit should be installed in an area that is clean and dry, allowing sufficient space on all sides for
routine maintenance and service. It should be located on a level floor or shelf free from vibrations and
sufficient to support the total weight of the machinery. Although the dryer package is a freestanding
unit, it may be secured by bolting the base to the floor but is not required. This standard dryer is
designed for indoor installation. Contact distributor if installing unit outdoors.
Installations at altitudes above 2500 feet (762 meters) may require adjustments to standard operating
conditions. The unit has been factory adjusted to operate at or near sea level. If installation is above
this altitude, contact your local distributor for corrected purge settings.
INLET CONDITIONS
A healthy, long-term, and trouble free compressed air supply design should be approached as a
complete system, not individual components. The air compressor; Intake location is vital to system
health; it should supply clean fresh air that is free from possible contaminant (e.g. ammonia, chlorine or
methane). Any contaminant entering the compressor intake will be concentrated by a factor of 8 due to
the compression process in a typical compressed air system.
A properly sized and maintained compressed air aftercooler is vital to maintaining an acceptable system
temperature range. GPS Series desiccant air dryers are designed to operate at rated flow with a
maximum inlet temperature of 100°F (37.7°C). Units can be oversized to accommodate higher inlet
temperatures up to 120°F (48.8°C). Inlet temperatures above 120°F (48.8°C) require custom designed
dryer equipment. In most cases temperatures can be kept below maximum operating by correctly
sizing or servicing the compressor aftercooler.
As dryer inlet temperatures rise above the design 100°F (37.7°C), the moisture holding capacity of
the air rises dramatically. This table represents the additional moisture load at elevated temperatures.
Inlet Temperatures
100°F (37.7°C)
105°F (40.5°C)
110°F (43.3°C)
115°F (46.1°C)
120°F (48.8°C)
Additional Load
0%
15%
32%
51%
75%

GPS Heatless Regenerative
Page 4 of 14
PRE-FILTRATION
As all regenerative desiccant dryers are designed to remove only water vapor, any possibility of liquid
water carryover to the desiccant dryer must be avoided. Coalescing pre-filtration will eliminate the
carryover of droplets, aerosols, and compressor lubricant liquids. Proper filtration will not only enhance
the dew point suppression capability of the dryer, but will also add years of life to the desiccant by
preventing fouling of the desiccant caused by compressor lubricants.
Coalescing pre-filtration of ISO Class-1(8573) with a max. oil carryover 0.008 PPM w/w is
required under the equipment warranty.
CONDENSATE
A typical compressed air system has multiple points that require condensate removal: the compressor,
the aftercooler, receiver tank and coalescing pre-filter. It is urgent that each of these drains is not
piped to a common header that will allow condensate to be pumped from a high-pressure location to a
low-pressure location. Some facilities have tried to install check valves to prevent backflow in a
common header system. This concept seems reliable in theory; however a drain system failure will be
imminent. The health of your compressed air dehydration system is contingent on a clean and properly
designed condensate removal system.
AFTER-FILTRATION
All regenerative desiccant dryers gradually produce hard and abrasive desiccant fines. These
contaminants should be removed with a high quality particulate after-filter capable of removing 1.0 µm
particles.
Particulate filters located downstream of Regenerative Air Dryers do not have automated drain systems.
The material collected should be held in the bottom of the housing; no draining is necessary. Simply
clean out the sump area as an element is replaced.
ECOMMENDED SYSTEM DESIGN
BLOCK & BYPASS
All compressed air dryer systems should have a bypass system to facilitate servicing the dryer and
filters without interrupting compressed air flow. Valves should be bubble-tight to prevent water vapor
migration around the system from the regions of high relative humidity to low relative humidity. The
bypass system should be capable of bypassing each filter or the dryer and any combination thereof.
Operation in this condition for extended periods of time is not recommended because of possible
system contamination (i.e. desiccant dust downstream, moisture downstream, or oil in the desiccant).

GPS Heatless Regenerative
Page 5 of 14
OPTIONAL BACK PRESSURE REGULATOR
For regenerative dryer applications where sudden downstream demand for compressed air frequently
occurs in such a manner to cause rapid pressure loss in the compressed air system, it is recommended
that a back pressure regulator be installed downstream of the dryer. The backpressure regulator will
maintain a constant pressure and reduce microburst velocity surges within the dryer. It will reduce the
possibility of desiccant bed fluidization, which accompanies rapid pressure fluctuation. By eliminating
fluidization and desiccant bed "bumping", the life of the desiccant charge will increase and after-filter
elements will not become prematurely clogged with desiccant fines.
Coalescing filters are also affected by dramatic flow swings or pressure changes. This problem is
identified by oil carryover through the element or even the destruction of the element.
PURGE EXHAUST PIPING
To eliminate noise pollution created by frequent tower depressurization or purge exhaust noise, the
purge exhaust may be piped outdoors or to a more remote area. This may also eliminate any problem
caused by indoor accumulation of condensed moisture from the purge exhaust. Extended purge
exhaust piping must not restrict the passage of purge air near atmospheric pressure.
If the equivalent length of extended purge exhaust piping does not exceed 15 feet, use pipe one size
larger than the dryer purge exhaust connection. If the equivalent length of extended purge exhaust
piping does not exceed 30 feet, use pipe two sizes larger than the dryer purge exhaust connection. For
remote purge piping in excess of 30 feet contact the factory for recommendations.
ELECTRICAL CONNECTION
The Nameplate/Data plate located on each unit identifies the power supply requirements
and maximum fuse specification. Units supplied with electrical junctions require a suitable
fused disconnect in compliance with the National and Local Electrical Code requirements.
Maximum fuse specification can be located on the Nameplate/Data Plate.
Check unit voltage supply as specified on the equipment data plate. The power feed should meet the
national electric code standard for amperage capacity of that unit. The feed voltage must be within 10%
of the specified data plate requirement. Reduced supply voltages can cause a reset of the control card
and elevated voltages can cause electronic components to fail. The (FLA) full load amps of any dryer
can also be found on the data plate directly below the specified voltage.
DESICCANT LOADING PROCEDURES
Models GPS-500 and larger require field loading of the desiccant material. Desiccant is not shipped in
the dryer vessels to avoid damage to the desiccant support screens and premature desiccant
breakdown. The screens are designed to support the load of the desiccant under operating conditions;
however, shipping conditions require the desiccant to be loaded on site.
THE PROCEDURE TO LOAD THE DESICCANT IS AS FOLLOWS:
1. Remove the pressure relief valves from the top of each of the dryer vessels.
2. Load 50% of the shipped desiccant quantity into each of the dryer vessels. The final level of the
desiccant will vary from unit to unit. If all of the desiccant will not fit in one or the other vessels, a slight
tapping or vibration will settle freshly loaded desiccant.
3. Replace the pressure relief valves on top of the dryer vessels to a pressure seal condition.

GPS Heatless Regenerative
Page 6 of 14
OPERATION
The operation of a GPS dryer is fully automated with
all sequencing and function controlled by an
automatic timing module or a programmable
controller.
Wet and dirty compressed air discharged from the
compressor enters the aftercooler, where the
compressed air temperature is reduced to near
ambient. The entrained liquids are released, and then
removed by a separator. The coalescing pre-filter
then removes any liquid moisture carryover present
after the separator. The compressed air still saturated
at the reduced temperature, but not containing any
gross liquids enters the regenerative dryer.
The saturated compressed air enters either the right
or left tower of the dryer depending on the control
sequence position. For ease of description, assume
the saturated compressed air is entering the right
tower. The compressed air passing through the right
desiccant tower gives up all of its water vapor to the
activated alumina desiccant. This cycle will continue
for 5 minutes on a standard model, or until the vessel
is saturated with the optional Demand Cycle
Controller. For more information on the operation of
the Demand Cycle Controller, refer to that section in
this manual.
While one tower is drying the process air, the other tower is in the regeneration mode. The
regeneration is accomplished by utilizing a regulated portion of dry compressed air called the purge
stream. The stream is expanded to near atmospheric pressure by passing through an orifice. This
expanded volume of dry air is then passed over the saturated desiccant bed to absorb and carry away
moisture. The now saturated purge stream exits to atmosphere through the left tower purge exhaust
valve and muffler. This process is maintained for 4 minutes and 30 seconds. At the end of this time
period the purge valve closes and allows the purge stream to repressurize the regenerated tower,
preparing it for the next cycle of adsorption. In larger systems, a small solenoid valve opens to assist
the purge stream in the repressurization process.

GPS Heatless Regenerative
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DEWPOINT DEMAND CONTROLLER
The Dewpoint Demand Controller is an option designed to limit energy consumption to the minimum
required for optimum dryer performance. The option works off the premise that not all compressed air
conditions are stable and continuous. Each desiccant tower is designed to adsorb the moisture load of
full rated flow and rated conditions for 5 minutes. For example; if at the end of 5 minutes your flow has
fluctuated from 20 to 100% of rated load, the desiccant bed has an unused adsorption capacity of
roughly 40%. At the end of the 5 minutes the demand cycle control holds the freshly regenerated tower
in a pressurized standby mode so the on-line tower can continue to adsorb moisture to the design limit.
While the dryer is in this standby mode no energy is being expended and the overall average energy
consumption is reduced. As the dew point meter (the heart of the Dewpoint Demand Control) signals
that the proper moisture loading of the on-line tower is approaching, the towers invert bringing the
standby tower on-line and beginning the regeneration of the previously saturated tower.
STARTUP
Pressurize the system with the dryer bypass open and the dryer inlet and outlet closed. Then open the
dryer outlet valve allowing it to pressurize the dryer from the outlet. By pressurizing the dryer
backwards through the outlet, it allows the control air system to be energized first and properly seat the
control and process valves.
S-L-O-W-L-Y pressurize the rest of the dryer by gradually opening the inlet valve upstream of the dryer.
This will allow compressed air to enter and completely pressurize the dryer. When the tower pressure
gauges indicate line pressure, close the bypass valve and allow compressed air to flow through the
entire dryer package.
Pressurization of the dryer should never be initiated by suddenly pressurizing the dryer towers from the
dryer inlet. The sudden rush of high velocity air in the desiccant bed would cause the desiccant bed to
fluidize. Desiccant fluidization will create desiccant breakdown and or excessive desiccant fines.
This section refers to systems with the optional Dewpoint Demand Systems only
The final step prior to initiation of the dryer is to verify flow to the dewpoint probe in the sample flow
cell. Open the isolation valve upstream of the sample cell filter. The sample cell is now pressurized.
An orifice in the sample cell outlet lets a small flow of air over the probe. After the orifice there is a
check valve that prevents atmospheric air from migrating into the sample cell when the compressed
air system is depressurized. The coil of tubing on the outlet of the sample cell is to prevent
atmospheric moisture from migrating into the sample cell during sampling.
Initiate the "power on" selector switch or push button. Almost immediately one tower will depressurize to
atmospheric pressure through the purge exhaust valve and muffler. At this time verify that the purge
flow indicator (pressure gauge in the purge loop piping) is reading the pressure indicated by the factory
tag located on the piping behind the gauge (the pressure setting for the flow indicator should be
between 45 & 55 PSIG). If the indicator does not match the tag, adjust the globe valve directly above
the indicator until the setting matches. This pressure/flow can be set only during a purge cycle (air
exiting the muffler). The setting will change during repressurization then return to the setting in the next
purge cycle. From this point the system should cycle as outlined in the operation section of this manual.
Once the purge flow is set it will fluctuate slightly during the day if the system operating pressure
fluctuates. It is best to set the purge flow during a time when the system pressure is at a low point, so
the dryer purge requirements are not starved during lower pressure operating periods.

GPS Heatless Regenerative
Page 8 of 14
SEQUENCE CONTROLLER
Time cycles are part of the equipment design that have been accurately set in the factory and should
not be field adjusted. Timing changes are possible for custom applications but always consult the
factory prior to changes. The following are the standard time cycles for your equipment.
Drying Each Tower
5 Minutes or indefinite period with the Demand Cycle Controller
option.
Purging Each Tower
4 Minutes / 30 Seconds
Drain Time Sequence
Field Adjustable
The standard heatless regenerative air dryer is controlled by a CMOS logic system designed
specifically for compressed air dryers. The controller is preset in its function with adjustments available
by moving jumper pins.
EXT/INT Configuration
Selects external or internal configuration for heating when HEAT is
selected on the HEAT/HTLS jumper pin.
50/60 CYCLE Power Input
Selects feed power frequency of 50 or 60 Hz.
HEAT/HTLS Type
Selects a basic design configuration of Heated or Heatless.
STD/TEST
Selects a standard operational timing sequence or a test sequence
The test cycles are for startup and troubleshooting do not operate in test for normal operation!
Type
Heated (HEAT)
Heatless (HTLS)
Time
Standard
Test
Open
Standard
Test
Open
Main
240 Min.
48 Min.
30 Sec.
300 Sec.
150 Sec.
20 Sec.
Purge
235 Min.
47 Min.
20 Sec.
260 Sec.
130 Sec.
10 Sec.
Heat
150 Min.
30 Min.
10 Sec.
(none)
(none)
(none)
Notes: 1. Open signifies that the jumper is completely removed and connects no pins.
2. Time sequence vs jumper status (assumes power frequency correlation)
Time Cycle Display
00 03
Hours : Minutes
The Time Cycle Display shows
the current online towers time
of operation (Adsorption)
Led Status Indicator
If the green led status indicator
is blinking it indicates the
controller is in an active
regeneration cycle. If the
indicator is solid, it indicates
that the controller is in a
demand standby mode waiting
for a signal from an external
source to complete a circuit
between terminal #11 & #12
If an optional PLC control is operating the dryer sequence, a program and manufacturer’s warranty will
be included with this manual. Consult factory prior to any changes to PLC programs.

GPS Heatless Regenerative
Page 9 of 14
MAINTENANCE
Pre & After Filtration
The Pre & After-filter element should be replaced whenever the pressure drop becomes excessive.
Differential pressure is the best method to gauge the need for element replacement. The
recommended maximum element differential is 10 PSIG. The pressure at which you should change
your elements should be determined by comparing the operational efficiency of your system (cost of
pressure drop vs. cost or the elements). Many facilities put filter replacement on an annual or bi-annual
schedule based on system contaminant load.
Control Air Filter
Frequent inspection of the control air filter is required so desiccant particulate does not restrict the
control air required for pneumatic actuation of dryer valves. The control air filter is generally replaced
when the particulate after-filter on the dryer is replaced.
Purge Muffler Maintenance
Purge mufflers prevent high noise levels from the cyclic depressurization of the desiccant towers. The
desiccant fines generated from normal operation will cause the muffler elements to become clogged,
which will restrict purge flow and cause insufficient regeneration. If the purge tower shows
backpressure during operation replace the muffler element.
The desiccant loading procedure can cause a large amount of desiccant dust to accumulate prior to
equipment startup. Most of this accumulation is blown out the purge exhaust valve during the first
hours of operation. The high volume of desiccant fines from startup limits the life of the initial purge
muffler element. It is recommended that the muffler element be replaced after the first 100 hours of
operation. Subsequent element replacements should be every 6 months to a year or as dictated by
regeneration tower backpressure.
Purge Rate Maintenance
An adequate supply of purge air is essential for proper regeneration of desiccant and good dewpoint
suppression. If your system pressure varies throughout the day set the purge pressure at a low period
so in low-pressure periods the purge flow is not starved. Always consult the factory prior to changing
operating conditions. The adjustable purge valve should be set to the following values for standard
equipment operating at standard conditions.
Model
Purge Set
Pressure
Model
Purge Set
Pressure
Model
Purge Set
Pressure
GPS-25
40
GPS-250
50
GPS-1400
45
GPS-35
40
GPS-350
50
GPS-1600
40
GPS-50
40
GPS-500
50
GPS-1800
50
GPS-75
45
GPS-650
50
GPS-2000
45
GPS-100
50
GPS-800
45
GPS-2250
45
GPS-125
50
GPS-1000
50
GPS-175
45
GPS-1250
45
Desiccant Maintenance & Replacement
Desiccant life is estimated at 3 to 5 years, however conditions differ with location. Contamination of
desiccant is a leading cause of accelerated failure. Close preventative maintenance of the coalescing
pre-filters will extend the life of the desiccant. Spent desiccant should be drained through the desiccant
drain port in the bottom of each tank. Desiccant alone is not hazardous and can be disposed of as a
general landfill product. Oil contaminated desiccant must be dealt with on the basis of the amount of oil
contamination.
Fresh desiccant should be added through the desiccant fill port, which is where the pressure safety
relief valves are located. Always leave adequate room above the desiccant bed to permit some bed
motion and expansion during dryer operation.
Be certain to only install the approved activated alumina that your Great Lakes Air Products
representative can provide; it excels with respect to dew point suppression capability and attrition
resistance. Various brands can cause excessive attrition, and poor dew point suppression.

GPS Heatless Regenerative
Page 10 of 14
TROUBLESHOOTING GUIDE - QUICK REFRENCE
Please read the entire troubleshooting section of the manual before proceeding with
any repairs or modifications. Several topics are addressed at several points in the
manual and understanding them all before you proceed will give you a much better
understanding of the entire process.
Because almost all problems with regenerative dryers will result in a bad Dewpoint it is assumed that
the condition of bad Dewpoint applies to this entire table.
PROBLEM
POSSIBLE CAUSE
Proceed to
Page
No / Bad
Regeneration
No / Low purge stream
See Purge Rate Maintenance
9
Regeneration back pressure
See Purge Exhaust System
10
Contaminated desiccant
See Desiccant Testing/Replacement
12
Cycle / Sequence
Failure
Low feed voltage
See ELECTRICAL CONNECTION
5
Process, Check, or
Solenoid Valve failure
See OPERATION
6
See Valve Integrity
11
See Intermittent Cycle Problems
12
Timing card failure
See SEQUENCE CONTROLLER
8
Dewpoint Demand Only
Dewpoint meter not
signaling
See Dewpoint Demand Controller
13
Excessive Inlet
conditions
Liquid at dryer inlet
See Filtration & Drains
10
High inlet temperature
See Ambient & Air Inlet
11
High flow at dryer inlet
See Ambient & Air Inlet
11
Low pressure at dryer inlet
See Ambient & Air Inlet
11
;
TROUBLESHOOTING TUTORIAL
Filtration & Drains
Identify the pre-filtration for the unit. It should be a high quality coalescing filter. Check that the drain
system is working properly and is not hard piped into other system drains. Hard piped drain systems
will inevitably pump liquid from one point of the system to the other because of operating differential
pressures. Check valves are utilized to overcome this problem in many facilities, but are prone to
failure from the usual debris in drain lines. If a system has a common piped drain system, water
downstream of the filters and dryer is almost impossible to identify.
Regenerative dryers are designed to remove vapor not liquid. Adequate filtration must be employed to
remove all liquid before entering the dryer.
If the dryer pre-filter has a differential pressure gauge, check to see that it reads at least 1 PSID. No
visible pressure drop is usually an indication of a ruptured filter element. If the coalescing filter is
showing large amounts of liquid being drained, it might be overloaded and bypassing liquid. Verify
upstream drains are functioning properly.
Purge Exhaust System
When the system is purging, check the tower pressure gauge on the purging tank. It should be at 0
PSIG (2 PSIG maximum). Any backpressure in the regeneration purge system will impede purge flow
and hinder the regeneration of the desiccant. If the system has mufflers, change the elements. This
should be done annually. If the system has the purge exhaust piped away, locate the cause for the
restriction and eliminate it. It is possible that a bad check valve or inlet valve is allowing process air
into the regeneration system, and this will overload the muffler or piping system. The next section
helps you identify a valve problem.

GPS Heatless Regenerative
Page 11 of 14
Ambient & Air Inlet
The capacity of a compressed air dryer is a combination of four operating conditions, flow, pressure,
temperature, and saturation. These parameters are commonly specified as SCFM at 100 PSIG,
100°F, and 100% saturated. When a system deviates from these standard parameters, the load on
the compressed air dryer changes. Elevated inlet temperature increases the moisture holding capacity
of each cubic foot of air entering the dryer. Reduced inlet pressures increases actual volume and
reduces the effectiveness of desiccant adsorption system. Changes in either of these conditions from
the standard design results in changes to efficiency and capacity of the compressed air dryer.
Flow Correction: The following chart offers multipliers that can be applied to your system flow rate to
calculate required dryer capacity at actual field conditions.
Dryer Inlet Temperature in °F
80
90
100
105
110
115
120
Dryer Inlet Pressure
PSIG (minimum)
70
0.75
1.01
1.35
1.54
1.78
2.04
2.36
80
0.67
0.90
1.21
1.38
1.60
1.83
2.12
90
0.60
0.82
1.09
1.24
1.44
1.65
1.91
95
0.58
0.79
1.05
1.20
1.39
1.59
1.84
100
0.55
0.75
1
1.14
1.32
1.51
1.75
110
0.51
0.69
0.92
1.05
1.21
1.39
1.61
115
0.49
0.66
0.88
1.00
1.16
1.33
1.54
120
0.47
0.64
0.85
0.97
1.12
1.28
1.49
125
0.45
0.61
0.82
0.93
1.08
1.24
1.43
150
0.38
0.52
0.69
0.79
0.91
1.04
1.21
Identify the compressed air inlet temperature to the dryer; if it is above 100°F and the system was not
designed for high inlet temperatures, it is most likely overloaded. Be sure to carefully identify the air
temperature, as 110°F can feel just warm through a steel pipe.
Identify the ambient operating conditions. If the unit is in ambient conditions above, 110°F Dewpoint
then operational efficiencies will suffer. Ambient temperatures at 120°F and higher will seriously
impair the dryer’s adsorption capacity.
Valve Integrity
Most of the valves on a regenerative dryer act to separate the high-pressure process-drying stream
from the low/atmospheric pressure regeneration system. By performing the following diagnosis, it is
possible to identify valve bypass and the severity of that bypass without even taking the unit out of
service.
Identify which tower/muffler is purging. Turn the purge control valve (Located between the tanks in
the purge piping) off completely. Check the muffler to see if the purge flow has stopped. If it has
stopped, half of the valves on the dryer are in good shape. If a small amount of air can be felt, then a
valve seat is leaking and needs to be repaired as soon as possible. If large amounts of air are
present, a valve has failed and immediate attention is required. Return the purge valve to the original
operating set points.
At this point, you have checked out half of the valves on the machine. In order to check the other half,
you will need to wait for the unit to switch towers so the process can be repeated on the other side of
the dryer. If you have a leak, it will be one of three points. They are listed in order of failure
probability. The only way to specifically identify which valve is failing requires depressurizing the unit;
removing the valves and inspecting them.
1. The front purge check valve above the opposite tank that is purging.
2. The back outlet check valve above the regeneration tank.
3. The inlet valve on the side of the tower that is regenerating. This valve is rarely the culprit. If
it is, you will most likely find air leaking out of the valve casting at a vent point indicating the
diaphragm has ruptured. The less likely option of a complete valve seizure is possible.

GPS Heatless Regenerative
Page 12 of 14
Intermittent Cycle Problems
There are three probable reasons that a system cycle will fail intermittently. The first possible reason
is the timer control card. This fault is very easy to verify with the help of a voltmeter. Use the meter to
match the control cycle to electrical outputs associated with the output diaphragm on page 9 of this
manual.
The second is a solenoid valve fault. To check this possibility verify that control air is applied to the
correct inlet or purge valve, by trying to remove the push-lock tubing on the top of each valve. This is
accomplished by pressing the locking ring between the brass fitting and the tubing and gently pulling
the tubing. If pressure is present, you will not be able to remove the tubing as it will be locked in place
by the pressure. If the tube has no control air, it will easily come out. Replace the tubing immediately if
it does come out your goal is to identify control signal not disconnect the tubing. Control air should be
present on the inlet valve that is closest to the purge valve venting purge air.
The opposite (online tank) inlet valve should not have control air and the opposite purge valve should
have control air because it is normally open. If the control card is sending the correct electrical signal
to the solenoid and the solenoid is not sending air to the correct process valve the solenoid is at fault.
If both the card and the solenoids check out and you have performed a valve check from
Valve Integrity in this, manual the problem must be check or inlet valve sticking. Replace the
appropriate left or right check valves and rebuild the inlet valves with complete rebuild kits.
Desiccant Testing or Replacement
Desiccant in a regenerative dryer has an average life of 5 years, provided the coalescing filter
upstream of the dryer is monitored and serviced regularly. Some types of system failures or lack of
filtration maintenance can damage desiccant before that period. We recommend that you pull a
desiccant sample and have it analyzed after approximately 3 years of service.
To pull a sample, de-energize and completely depressurize the dryer. Remove the lower
desiccant drain plug and fill a zip-lock bag full of desiccant. A quart bag with 1 to 2 pounds
of desiccant sample is usually sufficient. Label the bag left or right tower with the serial
number of the dryer.
Replacing the drain plug after it has been removed can be a messy and aggravating process without a
simple little trick. Before removing the plug, have a piece of cardboard just slightly larger than the
drain opening handy. Once the sample bag is full, cover the hole with your hand and work the
cardboard in the drain hole to stop the desiccant flow. Remove any debris from the threads reapply
thread sealant and replace the plug. The cardboard left in the tower will cause no problem to the
dryer operation.

GPS Heatless Regenerative
Page 13 of 14
Dewpoint Demand Controller (Optional)
The dewpoint demand system consists of three components. First, a probe that reads system dewpoint
and transmits a 4-20 ma signal to the second component, a digital display that interprets and displays it
in °F pressure Dewpoint. The third component is the 24V DC power supply that supplies power to the
probe for loop power signal and the probe’s auto calibration routine. All must be working in concert to get
an accurate dewpoint reading. Each dewpoint meter comes pre-programmed with manufacturers’
settings, and should not require any field adjustments. Cases, in which adjustments must be made, refer
to parameters instructions and the factory standard values chart below.
Press PAR to enter into PRO display, using the
F1▲/F2▼scroll to the program group that may need
adjustments. Once found, press PAR to select the
specific parameter that needs adjusting, followed by
F1▲/F2▼to change settings. Pressing PAR will finalize
any action. Pressing DSP at any time will return the
meter to the current dewpoint reading.
PAR
Initiates the Pro display, initiates settings and navigates the table to the right ➔
F1▲
Pro
Changes Settings and navigates the table up
and down
1-INP
rANGE
deCPt
round
FILtr
BANd
PtS
StYLE
INP 1
dSP 1
INP 2
dSP 2
F1▲
0.02A
0.00
0.01
1.0
0.10
2
YEY
4.00
-112
20.00
68
2-FNC
USr-1
USr-1
USr-1
F1
F2
rSt
Sc-F1
Sc-F2
F1▲
no
no
no
no
no
no
no
no
3-LOC
HI
LO
tOt
SP-1
SP-2
SP-3
SP-4
CodE
F1▲
loc
loc
loc
loc
loc
loc
loc
0
4-SEC
HI-t
LO-t
dSP-t
b-L1t
F1▲
0.0
0.0
2
off
5-tOt
dECPt
tBASE
SCFAC
Locut
P-UP
F1▲
0.0000
_in
1.000
-199.99
no
6-SPt
SPSEL
Act-1
SP-1
Src-1
HyS-1
tON-1
tOF-1
out-1
rSt-1
Stb-1
L1t-1
➔
SP-1
AB-LO
-40.00
rel
0.02
0.0
0.0
nor
auto
no
nor
Act-2
SP-2
Src-2
HyS-2
tON-2
tOF-2
out-2
rSt-2
Stb-2
L1t-2
F1▲
➔
SP-2
AB-HI
-20.00
Rel
0.02
0.0
0.0
nor
auto
no
nor
7-SrL
bAUd
dAtA
PAr
Addr
Abru
OPt
INP
tat
HILO
SPNt
F1▲
9600
7
Odd
0
yes
no
yes
yes
yes
no
8-Out
tyPE
ASIN
AN-LO
AN-HI
udt
F1▲
4-20
INP
-112
68
0.0
9-FCS
d-LEu
CodE
F2▼
F1▲
3
50
Bullet Points
1. Verify there is flow over
the sample cell. It should be
fed by an unrestricted
compressed air line. The flow
restriction is created by a
check valve and orifice on the
outlet of the sample cell, just
before the “pigtail” that
prevents ambient moisture
from backtracking to the
sensor.
2. Verify that the data
cable is securely connected to
the probe.
3. Verify the 24V DC
power supply is supplying the
correct voltage.

GPS Heatless Regenerative
Page 14 of 14
WARRANTY
Any standard GPS Series Regenerative Air Dryer manufactured by Great Lakes Air Products is
warranted free from defects in material and workmanship under normal use for a period of 2-Years
covering OEM replacement parts. Job site and or factory warranty labor is covered for the term of 1-
Year.The warranty applies to original purchaser effective at date of shipment from manufacturer’s
warehouse. The company’s obligation under this warranty is limited to repairing or, at its sole option,
replacing, during normal working hours at an authorized service facility of the company, any part
which in its judgment proved to be not was warranted within the applicable warranty period.
This warranty applies to equipment installed, operated and maintained in accordance with the
procedures and recommendations as outlined in the owner’s manual.
Great Lakes Air Products will not be responsible for the following items; component failure due to improper
or fluctuating voltage, maintenance items such as control air filter, muffler elements, dewpoint probes,
external wear items such as insulation or the exterior finish, desiccant that has been contaminated, freight
damages and or any parts not original to the dryer.
In all cases, seller must be given a reasonable opportunity to investigate and inspect any assumed
defects. At seller’s option, buyer must return any defective materials to seller’s plant or authorized
depot at buyer’s expense. Freight charges for returned or replacement machines or parts are not
the responsibility of Great Lakes Air Products. Seller’s liability whether on warranty contract or
otherwise shall be limited to repair or replacement of material found within such period to be
defective. In no event shall the seller be liable for consequential or special damages.
Great Lakes Air Products shall not be responsible for any incidental or consequential damages or
other costs resulting from the following; labor charges, delays, vandalism, negligence, fouling
caused by foreign material, damage from adverse air conditions, chemicals, or any circumstances
over which Great Lakes Air Products has no control.
The liability of Great Lakes Air Products for all loss or damage resulting from non-conforming goods
or tender, including breach of any and all warranties, shall be limited to refund of the purchase price
of the particular goods with respect to which the loss or damage occurred.
This warranty is in lieu of all other warranties oral or written, expressed or implied, including
warranties of merchantability or fitness for a specific purpose are hereby excluded and disclaimed.
This warranty shall not apply to any equipment, which has been subjected to misuse,
shipping damage, nonpayment, neglect or accident, nor shall it apply to any equipment that
has been repaired or altered by persons not authorized for each incident with a Great Lakes
Air Products authorization number.