Sterling SDA AP-1 User Manual
SDA Large AP-1 Control
Dehumidifying Dryer
Part Number: 882.00295.00
Bulletin Number: DH1-615-1
Effective: 04/28/2008
Write Down Your Serial Numbers Here For Future Reference:
_________________________ _________________________
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We are committed to a continuing program of product improvement.
Specifications, appearance, and dimensions described in this manual are subject to change without notice.
DCN No. ____________
© Copyright 2008
All rights reserved.
Shipping Info
Unpacking and Inspection
You should inspect the large dehumidifying dryer for possible shipping damage.
Thoroughly check the equipment for any damage that might have occurred in transit, such as
broken or loose wiring and components, loose hardware and mounting screws, etc.
In the Event of Shipping Damage
According to the contract terms and conditions of the Carrier, the responsibility of the
Shipper ends at the time and place of shipment.
Notify the transportation company’s local agent if you discover damage.
Hold the damaged goods and packing material for the examining agent’s inspection. Do not
return any goods before the transportation company’s inspection and authorization.
File a claim with the transportation company. Substantiate the claim by referring to the
agent’s report. A certified copy of our invoice is available upon request. The original Bill of
Lading is attached to our original invoice. If the shipment was prepaid, write us for a
receipted transportation bill.
Advise customer service regarding your wish for assistance and to obtain an RMA (return
material authorization) number.
If the Shipment is Not Complete
Check the packing list as back-ordered items are noted on the packing list. You should have:
; Large Dehumidifying Dryer
; Bill of lading
; Packing list
; Operating and Installation packet
; Electrical schematic and panel layout drawings
; Component instruction manuals
Re-inspect the container and packing material to see if you missed any smaller items during
unpacking.
If the Shipment is Not Correct
If the shipment is not what you ordered, contact the parts and service department
immediately at [262] 641-8610. Have the item and order numbers ready. Hold the items
until you receive shipping instructions.
Large Dehumidifying Dryers ii
Returns
Do not return any damaged or incorrect items until you receive shipping instructions from the
shipping department.
Large Dehumidifying Dryers iii
Table of Contents
CHAPTER 1: SAFETY................................................................7
1-1 How to Use This Manual.............................................................................................7
Safety Symbols Used in this Manual.....................................................................7
1-2 Warnings and Precautions..........................................................................................8
1-3 Responsibility..............................................................................................................9
General Responsibility...........................................................................................9
Operator Responsibility.........................................................................................9
Maintenance Responsibility.................................................................................10
Reporting a Safety Defect ...................................................................................11
CHAPTER 2: FUNCTIONAL DESCRIPTION...........................12
2-1 Models Covered in This Manual................................................................................12
2-2 General Description...................................................................................................12
Specifying a Drying System ................................................................................12
What is Desiccant?..............................................................................................12
The Closed Loop Drying System.........................................................................12
The Process/Regeneration Cycle........................................................................13
Sequence of Operation .......................................................................................13
2-3 Standard Features.....................................................................................................14
Auto Start Timer ..................................................................................................14
Mechanical Features...........................................................................................14
Electrical Features...............................................................................................14
2-4 Options......................................................................................................................15
Dewpoint Extend .................................................................................................15
Closed-Loop Regeneration .................................................................................15
2-5 Drawings and Diagrams............................................................................................16
Process Aftercooler.............................................................................................18
Aftercooler Design Specifications........................................................................18
Process Air Dust Collector...................................................................................18
Material Overdrying Protection............................................................................20
Mechanical Options.............................................................................................21
Electrical Options ................................................................................................21
Controller Options ...............................................................................................21
2-6 Safety Devices and Interlocks...................................................................................22
Dimensions and Specifications 9 Denotes availability..................................24
Mechanical Options 9 Denotes availability..................................................24
Electrical Features...............................................................................................25
Electrical Options ................................................................................................25
CHAPTER 3: MECHANICAL INSTALLATION ........................26
3-1 Uncrating the Equipment...........................................................................................26
3-2 Rigging and Placing Unit...........................................................................................26
3-3 Making Electrical Connections..................................................................................26
3-4 Making Gas Line Connections (Gas-Fired Models Only)..........................................27
3-5 Checking for Proper Blower Rotation........................................................................28
3-6 Making Dryer/Drying Hopper Process Air Connections ............................................29
Large Dehumidifying Dryers iv
Connecting Aftercooler/Precooler Cooling Water (Optional).....................................32
3-7
3-8 Using the Drying Hopper Air Trap.............................................................................33
CHAPTER 4: CONTROLS........................................................34
4-1 Controller Description................................................................................................34
4-2 Identifying Control Panel Components for the AP-1 Optional Controller................35
Disconnect Switch...............................................................................................35
Control Power Switch..........................................................................................35
Touch Screen......................................................................................................35
Alarm Horn & Light..............................................................................................35
4-3 Process Air Temperature and Conveying Process Controller...................................35
...................................................................35
4-4 Identifying Controller Screens...................................................................................36
Main Menu Screen...............................................................................................................36
Typical Dryer Screens..........................................................................................................36
System Screens..................................................................................................43
Alarm Screens.....................................................................................................48
Alarm Screen Example........................................................................................49
See Section 7-4: Alarms on p. 57 for alarm descriptions.............................................................49
4-5 Redundant Safety Controller Display........................................................................49
4-6 Setting the Redundant Safety Controller...................................................................50
CHAPTER 5: OPERATION.......................................................52
5-1 Start-up......................................................................................................................52
5-2 Using the Dryer Status Screen..................................................................................53
5-3 Alarms.......................................................................................................................54
................................................................................54
5-4 Alarm Descriptions....................................................................................................54
5-5 Shutdown ..................................................................................................................55
CHAPTER 6: MAINTENANCE .................................................56
6-1 Maintenance Schedule..............................................................................................56
6-2 Preventative Maintenance.........................................................................................57
Cleaning or Replacing the Process Air Filters.....................................................57
Cleaning or Replacing the Regeneration Filter....................................................58
Calibrating the Dirty Filter Alarm..........................................................................58
Checking the Dewpoint Control System..............................................................59
6-3 Corrective Maintenance ............................................................................................60
Symptoms of Worn Out Desiccant ......................................................................60
Replacing the Desiccant......................................................................................60
Replacing the Process Heater (Electric Dryers)..................................................61
Large Dehumidifying Dryers v
Replacing the Regeneration Heater (Electric Dryers) .........................................62
CHAPTER 7: TROUBLESHOOTING .......................................64
7-1 Introduction................................................................................................................64
7-2 Basic Troubleshooting...............................................................................................64
7-3 Determining Temperature Controller Errors or Sensor Errors...................................66
Using a Thermocouple........................................................................................66
Using a Platinum Resistance Thermometer........................................................66
CHAPTER 8: APPENDIX..........................................................67
8-1 Returned Material Policy...........................................................................................67
8-2 Technical Specifications............................................................................................68
Annex B Information............................................................................................68
8-3 Spare Parts List.........................................................................................................69
8-4 8-5 Dryer Identification (Serial Number) Tag.............................................................70
8-4 8-5 Dryer Identification (Serial Number) Tag.............................................................71
8-5 Technical Assistance.................................................................................................72
Parts Department ................................................................................................72
Service Department.............................................................................................72
Sales Department................................................................................................72
Contract Department...........................................................................................72
Large Dehumidifying Dryers vi
Chapter 1: Safety
1-1 How to Use This Manual
Use this manual as a guide and reference for installing, operating, and maintaining the large
dehumidifying dryer. The purpose is to assist you in applying efficient, proven techniques
that enhance equipment productivity.
This manual covers only light corrective maintenance. No other maintenance should be
undertaken without first contacting a service engineer.
The Functional Description section outlines models covered, standard features, and safety
features. Additional sections within the manual provide instructions for installation, preoperational procedures, operation, preventive maintenance, and corrective maintenance.
The Installation chapter includes required data for receiving, unpacking, inspecting, and setup
of the large dehumidifying dryer. We can also provide the assistance of a factory-trained
technician to help train your operator(s) for a nominal charge. This section includes
instructions, checks, and adjustments that should be followed before commencing with
operation of the dryer. These instructions are intended to supplement standard shop
procedures performed at shift, daily, and weekly intervals.
The Operation chapter includes a description of electrical and mechanical controls, in
addition to information for operating the dryer safely and efficiently.
The Maintenance chapter is intended to serve as a source of detailed assembly and
disassembly instructions for those areas of the equipment requiring service. Preventive
maintenance sections are included to ensure that the dehumidifying dryer provides excellent,
long service.
The Troubleshooting chapter serves as a guide for identification of most common problems.
Potential problems are listed, along with possible causes and related solutions.
The Appendix contains technical specifications, drawings, schematics, parts lists, and
available options. A spare parts list with part numbers specific to your machine is provided
with your shipping paperwork package. Refer to this section for a listing of spare parts for
purchase. Have your serial number and model number ready when ordering.
Safety Symbols Used in this Manual
The following safety alert symbols are used to alert you to potential personal injury hazards.
Obey all safety messages that follow these symbols to avoid possible injury or death.
DANGER! DANGER indicates an imminently hazardous situation that, if not avoided,
will result in death or serious injury.
WARNING! WARNING indicates a potentially hazardous situation or practice that, if
not avoided, could result in death or serious injury.
Caution! CAUTION indicates a potentially hazardous situation or practice that, if
not avoided, may result in minor or moderate injury or in property damage.
Large Dehumidifying Dryers Safety 7
Dryer Safety Tags
Tag Description Tag Description
Read Operation &
Installation Manual
PE
Hot!
Protected Earth
Ground
1-2 Warnings and Precautions
Our equipment is designed to provide safe and reliable operation when installed and operated
within design specifications, following national and local safety codes. This may include, but
is not limited to OSHA, NEC, CSA, SPI, and any other local, national and international
regulations.
To avoid possible personal injury or equipment damage when installing, operating, or
maintaining this equipment, use good judgment and follow these safe practices:
; Read and follow these operation and installation instructions when installing,
operating, and maintaining this equipment. If these instructions become
damaged or unreadable, additional copies are available from the manufacturer.
High Voltage Inside
Enclosure
Lifting Point
Earth Ground
; Follow all SAFETY CODES.
; Wear SAFETY GLASSES and WORK GLOVES.
; Work only with approved tools and devices.
; Disconnect and/or lock out power before servicing or maintaining the equipment.
; Use care when LOADING, UNLOADING, RIGGING, or MOVING this
equipment.
; Operate this equipment within design specifications.
; OPEN, TAG, and LOCK ALL DISCONNECTS before working on equipment.
You should remove the fuses and carry them with you.
; Make sure the equipment and components are properly GROUNDED before you
switch on power.
; When welding or brazing in or around this equipment, make sure VENTILATION is
ADEQUATE. PROTECT adjacent materials from flame or sparks by shielding with
sheet metal. An approved FIRE EXTINGUISHER should be nearby and ready for
use if needed.
; Do not restore power until you remove all tools, test equipment, etc., and the
equipment and related components are fully reassembled.
Large Dehumidifying Dryers Safety 8
; Only PROPERLY TRAINED personnel familiar with the information in this
manual should work on this equipment.
We have long recognized the importance of safety and have designed and manufactured our
equipment with operator safety as a prime consideration. We expect you, as a user, to abide
by the foregoing recommendations in order to make operator safety a reality.
1-3 Responsibility
These machines are constructed for maximum operator safety when used under standard
operating conditions and when recommended instructions are followed in the maintenance
and operation of the machine.
All personnel engaged in the use of the machines should become familiar with their operation
as described in this manual.
Proper operation of the machine promotes safety for the operator and all workers in its
vicinity.
Each individual must take responsibility for observing the prescribed safety rules as outlined.
All warning and danger signs must be observed and obeyed. All actual or potential danger
areas must be reported to your immediate supervisor.
General Responsibility
No matter who you are, safety is important. Owners, operators and maintenance personnel
must realize that every day, safety is a vital part of their jobs.
If your main concern is loss of productivity, remember that production is always affected in a
negative way following an accident. The following are some of the ways that accidents can
affect your production:
• Loss of a skilled operator (temporarily or permanently)
• Breakdown of shop morale
• Costly damage to equipment
• Downtime
An effective safety program is responsible and economically sound.
Organize a safety committee or group, and hold regular meetings. Promote this group from
the management level. Through this group, the safety program can be continually reviewed,
maintained, and improved. Keep minutes or a record of the meetings.
Hold daily equipment inspections in addition to regular maintenance checks. You will keep
your equipment safe for production and exhibit your commitment to safety.
Please read and use this manual as a guide to equipment safety. This manual contains safety
warnings throughout, specific to each function and point of operation.
Operator Responsibility
The operator’s responsibility does not end with efficient production. The operator usually has
the most daily contact with the equipment and intimately knows its capabilities and
limitations.
Plant and personnel safety is sometimes forgotten in the desire to meet incentive rates, or
through a casual attitude toward machinery formed over a period of months or years. Your
Large Dehumidifying Dryers Safety 9
employer probably has established a set of safety rules in your workplace. Those rules, this
manual, or any other safety information will not keep you from being injured while operating
your equipment.
Learn and always use safe operation. Cooperate with co-workers to promote safe practices.
Immediately report any potentially dangerous situation to your supervisor.
; NEVER place your hands or any part of your body in any dangerous location.
; NEVER operate, service, or adjust the dryer without appropriate training and first
reading and understanding this manual.
; NEVER try to pull material out of the dryer with your hands while it is running!
; Before you start the dehumidifying dryer, check the following:
• Remove all tools from the dryer;
• Be sure no objects (tools, nuts, bolts, clamps, bars) are laying in the
area;
; If your dryer has been inoperative or unattended, check all settings before starting.
; At the beginning of your shift and after breaks, verify that the controls and other
auxiliary equipment are functioning properly.
; Keep all safety guards in place and in good repair. NEVER attempt to bypass, modify,
or remove safety guards. Such alteration is not only unsafe, but will void the
warranty on your equipment.
; When changing control settings to perform a different mode of operation, be sure
selector switches are correctly positioned. Locking selector switches should only be
adjusted by authorized personnel and the keys removed after setting.
; Report the following occurrences IMMEDIATELY:
• unsafe operation or condition
• unusual dryer action
• leakage
• improper maintenance
• NEVER stand or sit where you could slip or stumble into the
dehumidifying dryer while working on it.
; DO NOT wear loose clothing or jewelry, which can be caught while working on the
dryer. In addition, cover or tie back long hair.
; Clean the dehumidifying dryer and surrounding area DAILY, and inspect the machine
for loose, missing or broken parts.
; Shut off power to the dryer when it is not in use. Turn the switch to the OFF position,
or unplug it from the power source.
Maintenance Responsibility
Proper maintenance is essential to safety. If you are a maintenance worker, you must make
safety a priority to effectively repair and maintain equipment.
Before removing, adjusting, or replacing parts on a machine, remember to turn off all electric
supplies and all accessory equipment at the machine, and disconnect and lockout electrical
and pneumatic power. Attach warning tags to the disconnect switch and air shutoff valve.
Large Dehumidifying Dryers Safety 10
When you need to perform maintenance or repair work on a dehumidifying dryer above floor
level, use a solid platform or a hydraulic elevator. If there is a permanently installed catwalk
on your dryer, use it. The work platform should have secure footing and a place for tools and
parts. DO NOT climb on the dehumidifying dryer, machines, or work from ladders.
If you need to repair a large component, use appropriate handling equipment. Before you use
handling equipment (portable “A” frames, electric boom trucks, fork trucks, overhead cranes)
be sure the load does not exceed the capacity of the handling equipment or cause it to become
unstable.
Carefully test the condition of lifting cables, chains, ropes, slings, and hooks before using
them to lift a load.
Be sure that all non-current carrying parts are correctly connected to earth ground with an
electrical conductor that complies with current codes. Install in accordance with national and
local codes.
When you have completed the repair or maintenance procedure, check your work and remove
your tools, rigging, and handling equipment.
Do not restore power to the dehumidifying dryer until all persons are clear of the area. DO
NOT start and run the dryer until you are sure all parts are functioning correctly.
BEFORE you turn the dehumidifying dryer over to the operator for production, verify all
enclosure panels, guards and safety devices are in place and functioning properly.
Reporting a Safety Defect
If you believe that your equipment has a defect that could cause injury, you should
immediately discontinue its use and inform the manufacturer.
The principle factors that can result in injury are failure to follow proper operating procedures
(i.e. lockout/tagout), or failure to maintain a clean and safe working environment.
Large Dehumidifying Dryers Safety 11
Chapter 2: Functional Description
2-1 Models Covered in This Manual
This manual provides operation, installation, and maintenance instructions for 600-3000 cfm
Large Dehumidifying Dryers with AP1 control. These dryers are available with electric
heaters or gas burners. Gas dryers are indicated with a “G” in the model number. Model
numbers are listed on the serial tag. Make sure you know the model and serial number of
your equipment before contacting the manufacturer for parts or service.
Our dehumidifying dryers are designed to generate heated, dehumidified air at carefully
controlled temperatures for use in closed-loop plastic drying systems. Dehumidifying dryers
are sized to meet the specific requirements stated by the Customer at the time of purchase.
2-2 General Description
Moisture removal from hygroscopic (moisture attracting) plastic pellets is an essential step in
the manufacture of high-quality plastic products.
Our Dehumidifying Dryers are used by the plastics industry to generate very low dewpoint
air that is heated to a controlled temperature for drying plastic pellets and regrind.
The drying system consists of a dry air source and drying hoppers with process heating
controls. The dry air source controls two primary sub-systems, the process air and the
regeneration circuit. Each dryer has a left and a right desiccant bed so that one bed can
regenerate while the other is in use. 2000-3000 cfm dryers feature two sets of desiccant beds,
for a total of four desiccant beds.
The drying system can be configured for one drying hopper or for as many as 20 hoppers.
The process air heater can be located on the dryer or on each individual drying hopper.
Heaters that are located on the drying hoppers can be set up with their own independent
controls or can be controlled centrally using the main dryer controller.
Specifying a Drying System
There were many variables considered in the selection of your drying system, including: type
of materials, residence time, throughput of the extruder or injection molding machine,
ambient air moisture and temperature, and the altitude at the processing site. Should your
operating environment change, we can advise you on necessary equipment, process time and
temperature modifications.
What is Desiccant?
Desiccant is a material that attracts and holds (absorbs) water from the air. The desiccant our
dryers use is a synthetic crystalline metal aluminosilicate that is blended with a clay binder
and formed into beads.
Absorbed water is driven from saturated desiccant by heating it to a high temperature
(reducing the desiccant's capacity to hold water) and forcing air through it. This moisture
removal process is called "regeneration".
The Closed Loop Drying System
These dehumidifying dryers force hot, dry air through the resin in the drying hopper, where
the air picks up moisture from the material and is drawn back to the dryer. In the dryer,
Large Dehumidifying Dryers Functional Description 12
moisture is stripped from the air by a desiccant bed. The dried process air is then re-heated
and delivered back into the drying hopper to dry material again.
This system is a "closed loop", because ambient (outside) air is never introduced into the
process air. The closed loop system is used by the manufacturer because the process air is
typically much drier than ambient air, even after carrying moisture out of the plastic resin.
Recycling process air maintains drying efficiency at a consistently high level.
The Process/Regeneration Cycle
There are two desiccant beds in a dryer up to 1500 cfm. Larger dryers have four beds (two
left and two right beds). While one desiccant bed is on-line in the process air loop, the other
is off-line being regenerated (see Figure 1).
When a desiccant bed is on-line, it absorbs moisture from the process air. The desiccant will
become saturated with moisture and need to be regenerated. The dryer automatically redirects
the process airflow to the second bed and starts regenerating the first bed.
During regeneration, air is heated to approximately 550°F and forced through the saturated
desiccant. The moisture driven off the desiccant is bled to the atmosphere. The regeneration
heater is then turned off while the regeneration blower continues to blow air through the
desiccant bed until it is cooled.
Figure 1: Regeneration Cycle
AD600-AD1500
Dryer Flow Schematic
Right Desiccant in
Regeneration
Dryer Valve
Regeneration
Blower
Regeneration
Filter
Insulated
Drying
Hopper
AD600-AD1500
Dryer Flow Schematic
Left Desiccant in
Regeneration
Dryer Valve
Regeneration
Blower
Regeneration
Filter
Insulated
Drying
Hopper
Regeneration
Heaters
Left Desiccant
Regeneration
Exhaust
Process
Heater
Right Desiccant
Process
Process
Blower
Filter
Regeneration
Heaters
Left Desiccant
Regeneration
Exhaust
Process
Right Desiccant
Heater
Process
Process
Blower
Filter
Sequence of Operation
When the dryer is started, the main air valve rotates 360º and then moves to place the last
successfully regenerated desiccant bed online. If the dryer was powered off using the main
power disconnect or E-stopped, then the regenerating bed is placed back into regeneration,
and the regeneration cycle is started over. The main air valve is allowed a period of time to
move from one position to the other. If the main air valve does not complete positioning
within the allotted time, then a “Main Air Valve Fail” alarm is generated and the dryer stops
the process air blower and disables the drying hoppers and regeneration circuit.
If the closed loop regeneration option is enabled, the regeneration closed loop valve moves to
the open loop position. The system always begins the cooling phase for a regeneration cycle
using ambient (open loop) air. The closed loop regeneration valve is allowed a period of time
to move from the closed to the open loop position and a “Closed Loop Valve” alarm is
generated if the valve fails to reach the commanded position within this time. This alarm will
disable the regeneration circuit but does not stop the process air system or drying hoppers.
Large Dehumidifying Dryers Functional Description 13
Once the main air valve and closed loop regeneration valve are in place, the process air
blower starts. The system monitors the process air blower’s overload, starter auxiliary contact
feedback and air pressure. Loss of any of these items when the process air blower is running
will cause the process air blower and the drying hopper’s process heaters to shut down.
The process air heaters (or gas burners, on gas-fired dryers) will turn on after a delay to allow
the process air blower to accelerate the operating speed.
During normal operation, one set of desiccant beds is connected to the process air circuit
while the other set is being regenerated. When the offline beds are done regenerating, they
will be switched into the process air circuit and the other beds will be regenerated. The
default bed switch setting is based on time. If the Dewpoint Switch option is enabled, the
beds will switch when the process air dewpoint reaches the dewpoint switch point. The
dewpoint option will automatically disable itself and an alarm will be generated if the
dewpoint sensor or related electronics fail.
2-3 Standard Features
Auto Start Timer
The autostart timer is used to automatically start and stop the dryer at the time you specify. It
can be programmed for one start and/or stop event per day for a week. When the Auto Start
Timer is enabled, the dryer will automatically start and stop at pre-programmed times. If the
dryer is stopped due to the Auto Start Timer, the DRYER STATUS message will indicate
that the Auto Start timer is active.
Mechanical Features
; 180ºF – 250ºF Drying temperature range
; High regeneration temperature control safeties
; 13X desiccant (molecular sieve)
; Easy to access process, regeneration, and combustion air filters.
; High pressure centrifugal blower
; Dew point +15º F to –40º F
Electrical Features
; Electrically-actuated air valve
; NFPA79, UL & CUL machinery electrical standards (Electric Dryers) includes:
• NEMA 12 controls, components & enclosure
• Non-fused electrical disconnect
• Solid state relays for heater control
• Branch fusing
• Lockable power disconnects
• Regeneration temperature control
• “Process high temp” indication light and audible alarm
• 7 day timer
Large Dehumidifying Dryers Functional Description 14
; NFPA86, UL, AGA & CGA machinery electrical standards (Gas Dryers)
; Available supply voltages of 208, 230, 460, 575/3/60 and 400/3/60
2-4 Options
Dewpoint Extend
The Dewpoint Extend option measures the temperature of the moist air as it is bled to the
atmosphere after regeneration. After a period of time, the bleed temperature will rise. This
condition, called "bed breakthrough" indicates that the bed is dry. At bed breakthrough, the
bleed air temperature peaks between 350°F and 400°F.
The regeneration heaters turn off automatically on bed breakthrough for additional energy
savings. A 550°F regeneration temperature will dry the desiccant beds sufficiently to produce
process air dewpoint of -40°F. In a properly sized system, this ultra-low humidity level will
be more than adequate to dry plastics to as little as .003% moisture.
Closed-Loop Regeneration
An optional regeneration closed-loop valve and heat exchanger can be used to close the
regeneration loop during the cooling portion of the regeneration cycle. If this option is
enabled on the dryer, air will be bled to the atmosphere until the heating portion of the
regeneration cycle is finished. Then, the regeneration closed loop valve will direct air through
a water-cooled heat exchanger and back into the regeneration loop (see Figure 2).
• Sequence shutdown switch
AD600-AD1500
Dryer Flow Schematic
Regeneration Closed Loop
Cooling is Activated
Regeneration
Heaters
Left Desiccant
Figure 2: Closed Loop Regeneration
Regeneration
Blower
AD600-AD1500
Dryer Valve
Optional
Regeneration
Closed Loop
Cooler
Regeneration
Regenerarion
Exhaust
Optional
Regeneration
Closed Loop
Valve
Filter
Dryer Flow Schematic
Regeneration Heating is
Activated
Regeneration
Heaters
Left Desiccant
Dryer Valve
Optional
Regeneration
Closed Loop
Cooler
Regeneration
Blower
Regeneration
Exhaust
Optional
Regeneration
Closed Loop
Valve
Regeneration
Filter
Large Dehumidifying Dryers Functional Description 15
2-5 Drawings and Diagrams
Process
Heater
Optional
Regeneration
Closed Loop
Cooler
Optional
Regeneration
Closed Loop
Valve
Regen.
Exhaust
Regeneration
Regen.
Filter
Blower
Insulated
Drying
Hopper
Process
Air Filter
Optional
After-cooler
Left Desiccants
Dryer Valve
Right Desiccants
Process
Blower
Airflow Schematic: 2000-3000 cfm dryers (4 desiccant beds). Left desiccant beds are
regenerating—closed loop regeneration is activated.
Regeneration
Process
Heater
Optional
Regeneration
Closed Loop
Cooler
Optional
Regeneration
Closed Loop
Valve
Regen.
Exhaust
Regen.
Filter
Blower
Insulated
Drying
Hopper
Process
Air Filter
Optional
After-cooler
Left Desiccants
Dryer Valve
Right Desiccants
Process
Blower
Airflow Schematic: 2000-3000 cfm dryers (4 desiccant bed). Left desiccant beds are
regenerating in open-loop regeneration mode.
Large Dehumidifying Dryers Functional Description 16
Filter Check
Gage
Differential
Pressure
Switch
PS
Thumb Screws
Cartridge Filter
Dust Shroud
Filter Retainer
F
E
Dust Level
Indicator
Optional dryer dust collector
Slide Gate
Clamp
Dust Pan
Large Dehumidifying Dryers Functional Description 17
Process Aftercooler
The optional aftercooler cools the moist air returning to the dryer from the drying hopper.
The aftercooler can cool the return air from 250ºF to about 150ºF. This maintains the dryer’s
efficiency and condenses the unwanted plasticizer from the air stream. The aftercooler
requires a cooling water connection (see Figure and page 25).
Figure 3: Process Aftercooler
Mounting
Brackets
High
Temperature
Gasket
Cooling Coil
Mounting Brackets
Cooling Coil
Pipe Gasket
Stainless Steel
Cooler Housing
Cooling Coil
Cooling Coil
Cover Plate
Cooling Coil
Pipe Gasket
Aftercooler Design Specifications
Entering water temp.
ºF ºC
85ºF 29ºC
Cooling Coil
Cover Plate
High
Temperature
Gasket
Stainless Steel Cooler
Housing
Process Air Dust Collector
The optional process air dust collector consists of a filter, dust can, pressure gauge, and
optional pressure switch (see Figure). The gauge will let you know whether it is time to clean
out your filters. The optional dirty filter alarm will be activated if the filter is dirty.
Large Dehumidifying Dryers Functional Description 18
Filter Check
Gage
Differential
Pressure
Switch
Figure 4: Process Air Dust Collector
Thumb Screws
PS
Cartridge Filter
Dust Shroud
Filter Retainer
F
Dust Level
Indicator
E
Slide Gate
Clamp
Dust Pan
Large Dehumidifying Dryers Functional Description 19
Material Overdrying Protection
Material Overdrying Protection is an automatic system used to reduce the chance of overdrying, and possibly melting, the resin in the drying hopper. Material Overdrying Protection
activates when the return temperature is above a set value, indicating that all the resin in the
hopper is dry.
The control system monitors the return air temperature and automatically changes the process
air setpoint to the SET BACK SETPOINT value when the return air temperature rises above
the set back temperature. The process air setpoint returns to normal when the return air
temperature falls below the SETUP TEMPERATURE value. The target values for
changing the process air setpoint can be adjusted on the Mat Protect screen.
Recommended Temperature Settings
Drying Temperature (ºF) 160 180 200 220 240 260 280 300 320 340 360
Setpoint 120 125 130 135 135 140 150 160 170 180 200
Figure 5: Material Miser/Air Balance Valve
Temperature
Probe
Valve
Proofing
Switch
Coupling
Drying
Hopper
Large Dehumidifying Dryers Functional Description 20
Mechanical Options
; Low temperature operation (120°F to 250°F)
; High temperature operation (250°F to 400°F)
; Precooler (Required for temperatures below 180°F, used with low temperature
operation)
; Aftercooler (Required for temperatures above 250°F, used with high temperature
operation)
; Plasticizer trap / Aftercooler w/filter
; Temperature Set Back
; Automatic airflow reduction valve (not for gas dryers)
; 13X desiccant
; Closed loop cooling valve
; Dew point +15°F to -80°F
; Sound insulation for under 85 DBA noise level
; Dust collector
Electrical Options
; Hopper mounting of the process heater box
; Remote operator interface (with standard controller only)
; Ethernet module for remote communication w/data logging
; CSA approval
; UL rating
; 400/3/50 supply voltage (includes CE compliance)
Controller Options
; Dew point meter w/regeneration on demand
; Phase detection
; Airflow monitoring
; Temperature setback
Large Dehumidifying Dryers Functional Description 21
2-6 Safety Devices and Interlocks
This section includes information on safety devices and procedures that are inherent to the
large dehumidifying dryer. This manual is not intended to supersede or alter safety standards
established by the user of this equipment. Instead, the material contained in this section is
recommended to supplement these procedures in order to provide a safer working
environment.
At the completion of this section, the operator and maintenance personnel will be able to do
the following:
• Identify and locate specific safety devices.
• Understand the proper use of the safety devices provided.
• Describe the function of the safety device.
Safety Circuit Standards
Safety circuits used in industrial systems protect the operator and maintenance personnel
from dangerous energy. They also provide a means of locking out or isolating the energy for
servicing equipment.
Various agencies have contributed to the establishment of safety standards that apply to the
design and manufacture of automated equipment. The Occupational Safety and Health
Administration (OSHA) and the Joint Industrial council (JIC) are just a few of the
organizations that have joined with the plastics industry to develop safety standards.
Every effort has been made to incorporate these standards into the design of the large
dehumidifying dryer; however, it is the responsibility of the personnel operating and
maintaining the equipment to familiarize themselves with the safety procedures and the
proper use of any safety devices.
Fail Safe Operation
If a safety device or circuit should fail, the design must be such that the failure causes a
“Safe” condition. As an example, a safety switch must be a normally open switch. The switch
must be held closed with the device it is to protect. If the switch fails, it will go to the open
condition, tripping out the safety circuit.
At no time should the safety device fail and allow the operation to continue. For example, if
a safety switch is guarding a motor, and the safety switch fails, the motor should not be able
to run.
Safety Device Lock-Outs
Some safety devices disconnect electrical energy from a circuit. The safety devices that are
used on the large dehumidifying dryer are primarily concerned with electrical power
disconnection and the disabling of moving parts that may need to be accessed during the
normal operation of the machines.
Some of the safety devices utilize a manual activator. This is the method of initiating the
safety lock out. This may be in the form of a plug, lever or a handle. Within this lockable
handle, there may be a location for a padlock. Personnel servicing the equipment should
place a padlock in the lockout handle.
Large Dehumidifying Dryers Functional Description 22
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