Altec AIR MHR Series User manual

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MHR SERIES
HEATLESS REGENERATIVE
AIR DRYERS

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TABLE OF CONTENTS
 3 - INTRODUCTION
 3 - INTRODUCTION MHR HEATLESS REGENERATIVE DRYING
 4 - APPLYING YOUR DRYER
 4 - DRYER SIZING AND CORRECTION FACTORS
 5 - INSTALLATION
 6 - INSTALLATION GUIDE
 7 - PRINCIPLE OF OPERATION
 7 - START UP
 8 - DRYER INDICATING LIGHTS
 9 - MAINTENANCE
 10 - PNEUMATIC SCEMATIC
 11 - ELECTRICAL SCHEMATIC
 12 - ECONO-PURGE CONTROLLER
 13/14 - TROUBLESHOOTING
 15 - CONTACT INFORMATION
IMPORTANT: READ THIS MANUAL CAREFULLY. IT CONTAINS INFORMATION ABOUT SAFETY
AND THE SAFETY OF OTHERS. ALSO BECOME FAMILIAR WITH THE PROPER INSTALLATION
AND CONTROLS OF THE AIR DRYER BEFORE OPERATING. ONLY QUALIFIED, TRAINED AND
LICENSED PERSONAL SHOULD SERVICE OR OPERATE THIS EQUIPMENT.
CAUTION: THIS MACHINE CONTAINS HIGH PRESSURE GAS AND ELECTICITY
READ CAREFULLY BEFORE ATTEMPTING TO INSTALL, OPERATE OR MAINTAIN YOUR
DRYER. PROTECT YOURSELF AND OTHERS BY OBSERVING ALL SAFETY
INFORMATION. FAILURE TO DO SO COULD RESULT IN PERSONAL INJURY AND/OR
PROPERTY DAMAGE. KEEP OWNER'S MANUAL FOR FUTURE REFERENCE.

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INTRODUCTION
Thank you for selecting an MHR series regenerative air dryer from Altec AIR . The regenerative air dryer is specifi-
cally designed and manufactured for drying and purifying compressed air generated by an air compressor.
Please read this instruction manual carefully before using the air dryer.
Please pay attention to the precautions in transportation, installation and operation that are listed in this manual.
Please use the dryer according to our application guide and be sure to perform the proper preventative mainte-
nance as recommended in this manual. Failure to perform the preventative maintenance will void the air dryer
warranty.
Direct any questions not covered in this manual to your distributor or call Altec AIR . @ 1-800– 521-5351. Before
calling with questions always have the air dryer model #, serial # and pressure gauge readings.
Service and maintenance can be obtained from your distributor. If you do not know your distributor please con-
tact the factory. Authorization must be obtained from Altec AIR before any parts or dryers are returned to the
factory. Altec AIR will not be responsible for anything returned without authorization.
ALTEC AIR MHR SERIES REGENERATIVE AIR DRYERS ARE SHIPPED AS COMPLETELY ASSEMBLED PACK-AGES, ALL
SIZES UP TO MHR500 AND ABOVE ARE FILLED WITH DESICCANT READY TO INSTALL. DESICCANT IS SHIPPED
LOOSE ON MODELS MHR800 AND ABOVE. THE TOWERS MUST BE FILLED WITH DESICCANT AT THE JOB SITE
ON MODELS MHR800 AND ABOVE. VISUALLY CHECK THE DRYER FOR DAMAGE THAT MAY HAVE OCCURRED IN
TRANSIT. IF THERE IS EVIDENCE OF DAMAGE, IMMEDIATELY ENTER A CLAIM WITH THE CARRIER, AND NOTI-
FY YOUR ARROW REPRESENTATIVE.
INTRODUCTION MHR HEATLESS REGENERATIVE DRYING
Twin tower regenerative air dryers are the dryers of choice when traditional refrigerated dryers do not provide suf-
ficient air quality required for today's applications. Altec AIR MHR series of heatless twin tower regenerative dry-
ers normally produce -40°F and can optionally be as low as -100°F dew points.
The dryer utilizes activated alumina for efficient drying of compressed air and will operate under extreme envi-
ronmental conditions. Activated alumina is aluminum oxide that is highly porous and exhibits tremendous surface
area (350 sq. meters/gram). Activated alumina is resistant to thermal shock and abrasion. It has a smooth, uni-
form ball size that prevents channeling of the air flow, which maintains low bed velocities. This maintains air con-
tact time for efficient moisture removal and minimal pressure drop. The MHR’s printed circuit board dryer
controls are housed in a NEMA 4X rated enclosure and provide control of pneumatically piloted valves
chosen for long life and high air flow.
ADDITIONAL SPECIFICATIONS
Maximum pressure drop of 2 PSIG
Maximum Working Pressure: 150 PSIG
Minimum Working Pressure: 75 PSIG
Maximum Inlet Temperature: 120°F
Minimum Inlet Temperature: 32°F
Standard Pressure Dew Point: -40°F
Electrical Construction: NEMA 4X
Standard Voltage: 120V/1PH/60HZ
AMPS: 0.5

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APPLYING YOUR AIR DRYER
TO ACHIEVE THE BEST DRYER PERFORMANCE, YOU SHOULD CAREFULLY CHECK THAT
THE DESIGN AND INSTALLATION REQUIREMENTS OUTLINED BELOW ARE SATISFIED.
(1) Standard operating pressure of your ALTEC AIR Dryer can range from 75 minimum to 150
maximum PSIG. Check dryer label to verify maximum service pressure. Air available for your air
usage will vary with operating pressure.
(2) The dryer should not be installed where compressed air and/or ambient temperature exceeds
120°F or drops below 32°F. Locate dryer to avoid extremes of heat and cold from other condi-
tions. Best results occur when dryer is located as close to point of use as practical. Where applica-
ble, dryer towers should be insulated to reduce heat loss. Avoid locating dryer outside or where it
is exposed to the elements.
Altec AIR dryers are sized according to air flow not pipe size. The dryer requires 10% to 15% of inlet
airflow (SCFM) for regeneration. The difference between the inlet and outlet flow is the amount of
purge air required. This air is purged to atmosphere and is not available for use downstream. certain
air supply to dryer meets your air demand plus purge air requirements.
DRYER SIZING AND CORRECTION FACTORS
SEE DRYER SIZING CORRECTION FACTORS TO PROPERLY SIZE DRYER BASED ON YOUR ACTUAL
OPERERATING CONDITIONS:
1. INLET AIR FLOW
2. INLET AIR PRESSURE
3. INLET AIR TEMPERATURE
OPERATING % OF INLET CAPACITY
PRESSURE PURGE LOSS PRESSURE MULTIPLIER
PSIG PSIG
250 8.40% 250 1.85
200 9.10% 200 1.70
175 9.90% 175 1.55
150 11.20% 150 1.35
140 11.60% 140 1.30
130 12.00% 130 1.25
120 12.70% 120 1.17
110 13.50% 110 1.09
100 14.60% 100 1.00
90 15.90% 90 0.90
80 17.50% 80 0.80
70 19.70% 70 0.70
60 22.50% 60 0.60
INLET CAPACITY
TEMP MULTIPLIER
DEG. F
120 0.67
110 0.76
100 1.00
90 1.13
80 1.14
EXAMPLE
To calculate the capacity of a MHR100 @ 120 psig and 90 F inlet temperature:
100 scfm (inlet) x 1.17 (pressure) x 1.125 (temperature) = 132 scfm (actual inlet capacity)
Actual Capacity of a MHR100 @ 120 psig and 90F = 132 scfm @ -
40F/C Pressure Dew Point*
*Contact Altec AIR or your local distributor for how to adjust your MHR for –100F/-73C Pressure
Dew Point Operation.

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INSTALLATION
DRYER LOCATION / VENTILATION
Install dryer only in a well-ventilated, clean, dry area and keep at least 3 feet between the dryer, other equipment
and the walls.
AMBIENT TEMPERATURES
Suitable ambient temperature for the refrigerant dryer is a MIN of 32°F to a Max of 110°F. The performance of the
dryer will be significantly decreased when the air dryer is subject to temperatures higher than 110°F.
INLET & OUTLET CONNECTIONS
Do not mix the air inlet and outlet air flow. INLET port is located at the bottom of the MHR dryer. The OUTLET port
is located at the top of the dryer. Pipe diameter should be sized according to air flow requirements. It is recom-
mended that a vibration absorber be installed on the dryer inlet and outlet to eliminate vibration from the compres-
sor.
FILTRATION, BYPASS VALVES, & CONDENSATE DRAINS
Appropriate pre and post filtration should be installed to protect the air dryer as well as the compressed air system.
IMPORTANT: PRE-FILTERS AND AFTER-FILTERS MUST BE INSTALLED BEFORE AND AFTER DRYER.
Compressed air entering the dryer must be cooled to at least 120°F.
Install Pre-Filters to "Inlet Air" connection on the bottom piping assembly. Pre-Filters protect desiccant beds from
contamination by oil, entrained water, pipe scale, etc., thereby extending dryer desiccant life.
Install After-Filter to "Outlet Air" connection on the top piping assembly. After-filters, located after the dryer,
help eliminate the possibility of desiccant dusting and carry over into the air system.
It is recommended to install a check valve after the dryer to prevent plant air from escaping out of the dryer
purge valve during periods of low or no plant air demand.
Isolation or 3-valve bypass should be installed on the air dryer outlet and inlet ports to allow for bypassing, depres-
surizing, proper maintenance, and servicing of the air dryer.
For all filters, water separators, tanks, etc - the proper condensate drains must be used to remove moisture from the
system. The user must run a drain line to an environmentally approved condensate collection/disposal system.
ELECTRICAL INSTALLATION
The dryer Data Label lists the electrical power requirements for the air dryer. The user must confirm that the line
voltage matches the voltage listed on the data label. (Warning – Operating the air dryer with improper line voltage
will void the warranty). Provide the proper size wire, disconnect switches and fuses in accordance with applicable
codes. Field wiring must comply with local and national fire safety and electrical codes. Standard dryer’s enclosures
and controls are designed to meet NEMA 4X electrical standards.
Connect power leads as indicated in the electrical schematic. Ground the frame properly.
MAXIMUM WORKING PRESSURE - 150 PSIG.
BREATHING AIR APPLICATIONS
This dryer has not been tested for breathing air applications. The owner is advised to do its own testing and use for
breathing air applications at owns risk.

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INSTALLATION GUIDE
1 – AIR COMPRESSOR 5 – MHR SERIES AIR DRYER
2 – ADF SERIES DRAIN VALVE 6 – AP SERIES AFTER-FILTER
3 – RECEIVER TANK 7 – 3 VALVE BYPASS
4 – AC SERIES PRE-FILTER
INSTALLATION A: Recommended for systems that consume less than or equal to the maximum capacity of the air compressor.
INSTALLATION B: Recommended for systems that may at times consume more than the maximum capacity of the air compressor.

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PRINCIPLE OF OPERATION
MHR Series heatless regenerative air dryers utilize the pressure swing principle of operation.
Compressed air saturated with water vapor passes through the inlet valve and flows upward through the desiccant in
tower "A''. Tower "A" is said to be "ON-LINE'.' The activated alumina desiccant adsorbs the water vapor in the com-
pressed air and the pressure dew point is lowered to a minimum of -40°F. The dried air then passes through a check
valve assembly to the outlet piping and then to the factory tools or equipment.
While the air is being dried in tower "A" the desiccant in tower "B" that adsorbed moisture in the previous cycle is
simultaneously regenerated. Tower "B" is "OFF-LINE'.' At the start of the regeneration cycle, tower "B" is depressur-
ized from the operating pressure to atmospheric pressure with a downward air flow and passes through the purge
valve and out the purge muffler. Regeneration continues with a portion of the dry air from tower "A" passing
through an orifice assembly and downward through tower "B" out to atmosphere.
This process takes about ten minutes to complete, with the drying cycle using about five minutes to provide the
desired dew point. The regeneration cycle takes approximately 45 seconds less to allow for re-pressurization before
switchover. The complete operation therefore consists of two cycles, one for drying and the other for regeneration.
Required purge air is generally 15% of rated flow. As pressure is a direct function of purge air, the higher the pres-
sure, the lower the purge.
START UP
1. SLOWLY PRESSURIZE THE DRYER
2. Energize electrical circuit by simply pressing the power ON/OFF button.
3. The Power ON LED will be illuminated when the dryer is in operation. When the electrical circuit has been ener-
gized, the control circuit board will start to operate and automatically initiate dryer operation. The timer is factory
set, so that no field adjustment is necessary.
4. Adjust Purge Adjustment Valve so that the center Purge Pressure Gauge reads appropriate pressure:
MODEL PURGE
PRESSURE
MODEL PURGE
PRESSURE
MHR75 20 PSIG MHR520 35 PSIG
MHR100 20 PSIG MHR620 50 PSIG
MHR125 40 PSIG MHR800 40 PSIG
MHR150 40 PSIG MHR1000 45 PSIG
MHR200 20 PSIG MHR1200 50 PSIG
MHR250 30 PSIG MHR1600 50 PSIG
MHR350 45 PSIG MHR2000 40 PSIG

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DRYER INDICATING LIGHTS
Tower Drying – The Tower Drying LED will be illuminated indicating which tower is online and in the
drying mode.
Tower Regenerating – The Tower Regenerating LED will be illuminated indicating which tower is off
line and in the Regenerating mode.
Repressurizing – The Tower Repressurizing LED will be illuminated indicating which tower is online
and in the drying mode.
Failure to Shift - The Failure to Shift LED will be illuminated when a dryer shift failure has occurred.
The shift failure was due to a Failure to Depressurize or Failure to Repressurize. Observe dryer operation
to determine which failure caused the Failure to Shift and refer to Troubleshooting Guide.
Power ON – Illuminated when the switch is in the ON position.

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MAINTENANCE CAUSE INJURY SHOULD YOU ATTEMPT TO DISASSEMBLE
WHILE PRESSURIZED.
Purge Muffler
At high pressures a clogged muffler could result in a high backpressure and could result in mechanical failure or
personal injury. For this reason the purge muffler must be periodically checked for any restrictive debris. If pres-
sure is observed on the offline tower replace muffler immediately.TO AVOID INJURY, DEPRESSURIZE DRY-
ERRFORMI
Purge Valves
Should either of the normally closed purge valves fail to operate check the following:
1. Check air signal to valve.
2. If air signal is present; disassemble, clean and replace diaphragm and seals.
3. If no air signal is present; see solenoid valve information in Maintenance Section.
Inlet Valves
Should either of the normally open inlet valves fail to operate check the following:
1. Check air signal to valve.
2. If air signal is present; disassemble, clean and replace diaphragm and seals.
3. If no air signal is present; see solenoid valve information in Maintenance Section.
Outlet and Purge Check Valves
NOTE: Signs of a faulty outlet and/or purge check valve include;
 Failure to Depressurize Alarm
 System air is being drained and compressor is running at below normal efficiency.
 Periodically check the outlet and purge check valves for an absolute seal. Procedure:
 Close purge adjustment valve. Verify offline tower pressure is 0 PSIG.
 Check offline purge muffler for airflow. No airflow should be present.
 If no airflow is present, the outlet and purge check valve have a positive seal. Repeat procedure next
cycle to check opposite outlet and purge check valves
 If airflow is present, the outlet and/or purge check valves do not have a positive seal. Clean and/or re-
place corresponding check valves. See air flow diagram for corresponding check valves.
Pilot Air-Filter (Located at Outlet)
For maximum filtration efficiency, service the element 2x per year.
PREVENTATIVE MAINTENANCE SCHEDULE
Daily
 Check and record inlet pressure, temperature and flow.
 Verify that it is within specifications.
 Check tower pressure gauge readings within operating tol-
erance.
 Check tower pressure gauges for proper dryer cycling.
 Verify that pressure in purging tower is 5 PSIG or less.
 Verify that prefilters and off-line differential pressure is
within operating limits.
Semi-Annually
 Check outlet dew point.
 Blow down relief valves.
Monthly
 Check your operating conditions: inlet flow, inlet pressure,
and inlet temperature.
 Check prefilters and after filters.
 Check dryer cycle and sequence of operations, (i.e. drying and
regenerating).
Annually
 Check desiccant and replace if necessary.
 Inspect and clean pilot operated valves and re-
place packing as necessary.
 Inspect and clean solenoid valves, check
valves and purge lines.
 Test electrical components, replace as neces-
sary.
Quarterly (3 Months)
 Check pilot air filter element and clean.
 Replace prefilter and afterfilter elements.
3-Years
 Replace desiccant (if necessary)

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PNEUMATIC CONTROLS

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ELECTRICAL SCHEMATIC

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ECONO-PURGE CONTROLLER (OPTIONAL)
NOTE: At inial startup and during the first six months of connuous dryer operaon, the Econo-Purge Controller
logic SHOULD NOT BE ACTIVATED. A condioning process must occur in new desiccant, this will allow
the desiccant to remove its precise water vapor capacity from the airflow.
The funcon of EPC is to conserve energy by eliminang unnecessary dryer cycling, purge air consumpon, and com-
pressor power consumpon.
The EPC works by ulizing a moisture sensive probe to measure the water vapor content of the outlet air flow. The
moisture content of the sample air stream indicates the wetness of the drying tower's desiccant bed. The purpose of
the probe and its associated electronics is to first measure the "wetness" of the air within the desiccant beds and
then regenerate the desiccant beds only when the moisture loading reaches a pre-set maximum, desired dew point.
The ECONO-PURGE CONTROL Plus is packaged with a digital dew point controller and High Humidity Alarm opon.
The digital dew point controller allows the end user to pre-set a desired dew point at which the dryer will start the
Energy Savings Mode. This controller also allows the end-user to pre-set a dew point at which a high humidity alarm
condion would occur. See High Humidity Alarm opon for full descripon. See the digital dew point controller Own-
ers Manual enclosed for changing desired dew points.
NOTE: Energy Savings Mode is factory preset
to acvate at -30° F dew point. High Hu-
midity alarm is factory preset to +10° F dew
point.

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PROBLEM PROBABLE CAUSE CORRECTIVE ACTION
Elevated Dew Point Insufficient purge rate 1. Check purge flow settings.
2. Check purge piping for obstruction
3. Clean purge piping and muffler
Inlet air/gas pressure below
source/design condition
1. Check pressure
Flow rate higher than design
for condition
1. Check flow rate and
2. Determine what caused increased demand
Inlet temperature above de-
sign for condition
1. Check after-cooler
2. Clean & service as necessary
Entrained water entering the
desiccant bed
1. Check air/water separator drain operation
2. Check pre-filter drain operation
3. Replace desiccant and/or dryer if necessary
Desiccant contaminated by oil 1. Check pre-filter element
2. Check pre-filter drain operation
3. Replace desiccant and/or dryer if necessary
Excessive Pressure
Drop in Air Dryer
Excessive flow rate 1. Check flow rate
2. Located what caused increased demand
Inlet pressure below design
for condition
1. Check pressure
Failure to Shift Tow-
ers from Drying to
Regenerating Service
No input power 1. Check input voltage
Defective timer 1. Check input and output voltages
Defective solenoid valve 1. Check input voltage to solenoid valve
2. Check outlet air flow from solenoid valve
No pilot air 1. Check pilot air-line for blockage
2. Check to see if pilot air-line filter is clean.
3. Replace element if needed
Defective inlet valves 1. Check pilot air source
2. Refer to steps above if no pilot air detected
TROUBLESHOOTING GUIDE

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PROBLEM PROBABLE CAUSE CORRECTIVE ACTION
Dryer Fails to Pres-
surize
Faulty purge valve 1. Check purge valve and its solenoid valve.
2. Refer to earlier steps if no pilot air is detect-
ed
3. Check timer sequencing
Dryer De-pressurizes
Rapidly
Purge valve does not close;
dryer depressurizing through
purge valve
1. Check purge valve and its solenoid valve
2. Refer to earlier steps if no pilot air is detect-
ed
3. Check depressurization timer circuit
Dryer Fails to Purge Purge valve does not close;
Purge valve stuck in closed
position
1. Check timer micro-switch
2. Check solenoid valve.
3. Repair and replace if necessary
Purge muffler is clogged 1. Refer to Purge Muffler replacement proce-
dure.
Purge muffler is clogged 1. Refer to Purge Muffler replacement proce-
dure.
Outlet check valve stuck open 1. Clean check valve
2. Replace check valve if issue persists
Excessive Back-
Pressure in Regener-
ating Tower (above 5
PSIG)
TROUBLESHOOTING GUIDE

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