Sterling STT40, STT70 User Manual
Operation Instructions
Dehumidified air dryer
STT40
STT70
Sterling Material Processing
Sterling Material Processing
5200 West Clinton Ave.
Milwaukee, WI 53223
Telephone: (414) 354-0970
Fax: (414) 354-6421
www.sterlco.com
Technical service:
Service department
Telephone: (800) 423-3183
Edition: 07/03
STT40 / STT70
These operation instructions are for*:
(* please fill in personally)
Serial number:
Year of manufacture:
Date of Delivery:
Number of delivery:
Date commissioned:
Location:
Group of machines:
2
STT40 / STT70
Sterling Material Processing retains all rights to change the information in these operation
instructions at any time without notice.
We assume no liability for any errors from direct or indirect damage resulting in context with these
operation instructions.
Copying, translation or publication in any form except for personal use by the purchaser requires
approval from Sterling Material Processing.
All rights reserved.
3
STT40 / STT70
Table of contents
1. General Information................................................................................................. 1-1
1.1. Warnings and symbols.......................................................................................... 1-1
1.2. Explanations and information............................................................................... 1-3
1.3. Legal basis ............................................................................................................1-3
1.4. Field of application ...............................................................................................1-3
1.5. Notes on Usage ..................................................................................................... 1-3
2. Safety instructions.................................................................................................... 2-1
2.1.1. Assembly...................................................................................................... 2-3
2.1.2. Operation ..................................................................................................... 2-3
2.1.3. Maintenance................................................................................................. 2-4
2.2. For the safety of the device................................................................................... 2-5
3. Start up..................................................................................................................... 3-1
3.1. Initial Operation.................................................................................................... 3-2
3.1.1. Switching on the Dryer ................................................................................3-2
3.2. Continuous Operation ...........................................................................................3-4
3.2.1. Switching the Dryer on ................................................................................3-4
3.2.2. Setting the Drying Temperature...................................................................3-5
3.3. Switching the Dryer off ........................................................................................3-7
4. Error and error correction ........................................................................................4-1
5. Maintenance............................................................................................................. 5-1
5.1. Maintenance schedule........................................................................................... 5-3
5.2. Preventative Maintenance..................................................................................... 5-4
5.2.1. Servicing Process Air Filters .......................................................................5-4
Cleaning or Replacing the Return Air Filter............................................................ 5-5
5.2.3. Servicing the Dew Point Monitor ................................................................ 5-6
5.3. Corrective Maintenance........................................................................................ 5-7
5.3.1. Symptoms of Worn Desiccant .....................................................................5-7
5.3.2. Replacing Worn Desiccant ..........................................................................5-8
5.4. Disposing of Drying Agents ................................................................................. 5-9
5.5. Replacing the Process Heater.............................................................................. 5-10
5.5.1. Replacing/Cleaning the Cooling Coils ...................................................... 5-11
5.5.2. Replacing the regeneration heating coil..................................................... 5-12
5.6. Cleaning the Drying Hopper............................................................................... 5-13
6. Functional description............................................................................................ 6-15
6.1. General Information............................................................................................ 6-16
6.2. Drying Hopper (Optional)................................................................................... 6-19
6.2.1. Hopper Heater............................................................................................ 6-20
6.3. Connection to a Pneumatic Conveying System (Optional) ................................ 6-22
6.4. Return Air Cooler (Optional)..............................................................................6-22
7. Transporting, Assembly and Storage....................................................................... 7-1
7.1. Transporting and Packing .....................................................................................7-2
7.2. Assembly............................................................................................................... 7-3
7.3. Storage .................................................................................................................. 7-3
8. Assembly instructions.............................................................................................. 8-1
8.1. Installation of the exhaust fan for regeneration of exhaust air.............................. 8-2
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STT40 / STT70
8.2. Grounding the equipment against electrostatic charging...................................... 8-2
8.3. Electrical Connection............................................................................................ 8-3
8.4. Connection of Return Air Cooler (Optional)........................................................ 8-4
9. Troubleshooting .......................................................................................................9-1
9.1. Introduction........................................................................................................... 9-1
9.2. Determining Temperature Controller Errors or Sensor Errors .............................9-4
Using a Thermocouple............................................................................................. 9-4
Using a Platinum Resistance Thermometer............................................................. 9-4
10. Technical data ........................................................................................................10-5
10.1. STT40 ...............................................................................................................10-5
10.2. STT70 ...............................................................................................................10-5
10.3. Dimension Sheet ...............................................................................................10-6
11. Spare parts list........................................................................................................ 11-1
12. Electrical manual ...................................................................................................12-1
13. Accessories ............................................................................................................13-1
5
STT40 / STT70
1. General Information
These operation instructions are addressed to all users of this
device.
These operation instructions must be followed by every person
working on or with the unit.
1.1. Warnings and symbols
The following warnings and symbols are used in these operating instructions:
This symbol indicates danger to life! Fatal or serious injury is
possible if the corresponding instructions, regulations or
warnings are not observed.
/ This symbol indicates that serious injury is possible if the
corresponding instructions, regulations or warnings are not
observed.
) This symbol indicates that extensive damage to equipment is
possible if the corresponding instructions, regulations or
warnings are not observed.
This symbol indicates that information is important for becoming
familiar with the equipment, i.e. technical specifications.
This symbol indicates that a technical term is explained at this
point.
General Information 1-1
STT40 / STT70
When disposing of drying agents / batteries / oil, observe all
official rules.
Caution: High noise pollution !
For anyone working on the equipment, hearing protection
should be worn.
Avoid impairment of hearing!
Caution: Danger of being crushed !
Disconnect the equipment from the main power supply before
starting maintenance procedures. All compressed air pipes on
the equipment should be depressurized before starting
maintenance work.
Caution: Danger, surface is hot !
Before starting any work, wait until all parts have cooled down
sufficiently. Avoid touching any of these parts!
Caution: Danger, surface is slippery !
Remove any granules remaining on the ground.
Caution: Danger, electrical shock hazard !
Observe that the control system is still under voltage even
when the main power switch is switched off.
General Information 1-2
STT40 / STT70
1.2. Explanations and information
Various terms and designations are used in these operating instructions to ensure clarity.
Therefore please note that the terms used in the text stand for the corresponding explanations
listed below.
• Equipment: ”Equipment” can mean an individual unit, a machine or an installation.
• Operating personnel: The ”operating personnel” are persons operating the equipment under
their own responsibility or according to instructions.
• Operator: The ”operator” of the equipment (production manager, foreman, etc.) is the person
responsible for all production sequences. The operator instructs the operating personnel
what is to be done.
• Operating instructions: The ”operating instructions” describe the interaction of the equipment,
production sequences or methods. The operating instructions must be compiled by the
operator of the equipment.
• Equipment foreman: When several operating personnel work on one machine, the
”equipment foreman” coordinates the operating sequences. The equipment foreman must be
appointed by the operator.
• Trained personnel: ”Trained personnel” are persons whom, due to their training, are
authorized to carry out the required work.
1.3. Legal basis
See “Manufacturer’s Certificate” resp. “Certificate of Conformity”.
1.4. Field of application
This dryer has been manufactured to dry thermoplastic granules and regrind before processing.
This machine removes all remaining moisture from the granules both inside and out, regardless
of climate or ambient air conditions.
1.5. Notes on Usage
• Experienced operators can begin directly with the chapter on “Start-up” if the unit has been
properly installed.
• If the unit has not been installed yet, observe the instructions in the chapter on “Assembly
Instructions” and “Transport, Assembly and Storage”.
General Information 1-3
STT40 / STT70
2. Safety instructions
These safety instructions apply to all persons around the
operating equipment.
Please inform all persons around the operating equipment of the
direct and indirect hazards connected with it.
These operation instructions are to be used by all persons
assigned activities connected with the equipment.
Knowledge of the English language is a prerequisite.
For your safety, ensure that the operating personnel are familiar
with the operating instructions and the function of the equipment.
Safety instructions 2-1
STT40 / STT70
2.1 General
The operating personnel of this equipment must be at least 16 years old.
Please read these operation instructions carefully before operating the equipment for the first
time. Contact us should questions arise. This avoids injury and damage to equipment!
These operation instructions must be kept available at all times at the place where the equipment
is operating. Improper operation results in danger of accidents!
Please note that not all conceivable cases regarding operation or maintenance of the equipment
can be covered in these operating instructions.
Please observe all safety instructions and warnings on the equipment. This avoids injury and
damage to equipment!
All work on the equipment must be carried out by persons whose qualifications are specified in
the pertaining chapters of the operation instructions. Improper operation results in danger of
accidents!
The proper work clothes must be worn during any work on the equipment is performed. This
avoids injury!
The local regulations and requirements pertaining to this equipment must be observed.
Disconnect electrical components from the main power supply before working on them. Caution:
Danger, electrical shock hazard!
Compile a detailed sequence of operating procedures to be carried out on this equipment based
on this Operation Instruction Manual. Improper operation results in danger of accidents!
Observe that the control system is still under voltage even when the main power switch is turned
off. Caution: Danger, electrical shock hazard!
Safety instructions 2-2
STT40 / STT70
2.1.1. Assembly
Compare the connected loads with those of the main power supply. Danger, electrical shock
hazard!
When using lifting gear, please observe the pertaining regulations. Caution: Danger of accidents!
Do not modify, add other equipment or change the design of the equipment without the approval
of the manufacturer. Caution: Danger of accidents!
Attachments not supplied by Sterling must be manufactured in accordance with safety regulation
EN 294. Danger of accidents!
The equipment may only be operated when all the associated components are properly
connected in accordance with the relevant regulations. This avoids injury and damage to
equipment!
Operate the device only if all its components are grounded. Danger, electrical shock hazard!
Please note for installation that the equipment is top-heavy. Danger exists that it may topple over!
Take care that the device is not standing on the main power cable. This will prevent danger to
people and material!
2.1.2. Operation
Appoint a foreman to be responsible for the equipment.
Ensure that the operating personnel are provided detailed instruction in the operation of the
equipment. Improper operation results in danger of accidents!
When the main power switch is turned off for reasons pertaining to safety, it must be secured
against unauthorized activation. Caution: Danger of accidents!
Repair work must be carried out by trained personnel only. Caution: Danger of accidents!
Never operate the equipment when partially dismantled! Danger! Limbs may be caught in
machinery! Electric shock!
In case of malfunction, shut down the equipment immediately. Have malfunctions corrected
immediately. Danger of accidents!
This machine is intended only for the drying of granulated plastics. Any other use is contrary to
specifications.
This equipment is not suitable for food processing.
The safety instructions of any connected machines must be followed.
Please note that sound levels exceeding 85 db(A) may cause long term damage to your health.
Use the appropriate ear muffs. This avoids impairment of hearing!
Please note that the drying cells, drying hoppers and piping grow hot during use. Avoid touching
any of these parts! Danger: Injury through burns!
Never operate the dryer without side panels. Danger: Limbs may be caught in machinery! Injury
through burns!
When drying plastics which emit gases dangerous to human health, take care that the
regeneration exhaust air is disposed of without polluting the environment. This will prevent danger
to people and material!
Safety instructions 2-3
STT40 / STT70
2.1.3. Maintenance
Before starting maintenance work, appoint a supervisor.
Inform personnel responsible for the system before beginning maintenance work. Caution:
Danger of accidents!
Disconnect the equipment from main power supply before starting maintenance procedures to
ensure that it cannot be switched on unintentionally. Caution: Danger of accidents!
All pipes, hoses and connections should be checked regularly for leaks and damage. Any faults
which arise should be corrected immediately. Danger of accidents!
Depressurize all compressed air piping before starting maintenance work. Danger of accidents!
Air filters should only be cleaned/replaced when the the main power switch is off and the blower
has stopped. This avoids injury and damage to equipment!
Any maintenance work on the equipment should only be started when the main power switch is
off and the blower has stopped. This avoids injury and damage to equipment!
Check the v-belts of the blower only when the main power switch is turned off and the blowers
have stopped. Caution: Danger of accidents!
Open drying hoppers only if they are completely empty. Danger of accidents!
Never open drying hoppers while the device is in operation. Danger: Injury through burns!
Open drying hoppers only if they have been sufficiently cooled down. Danger: Injury through
burns!
Before beginning maintenance work, wait until the drying cells, drying hoppers and air piping
have cooled down sufficiently. Avoid touching any of these parts! Danger: Injury through burns!
Remove any granules remaining on the ground. Danger of accidents!
Lock the wheels in place after installation if the dryer is mounted on a movable frame. This will
prevent danger to people and material!
Safety instructions 2-4
STT40 / STT70
2.2. For the safety of the device
Never change settings without carefully assessing the consequences.
Use only original Sterling spare parts.
Observe the maintenance instructions.
Keep a record of all maintenance work and repairs.
Please note that electronic components can be damaged by static discharge.
Before initial operation and at regular intervals, make sure that no electrical connections are
loose.
Never readjust sensors without exactly knowing their functions.
Please ensure that the storage temperature is between 32 to +131 °F (0 and +55 °C).
Please ensure that the operation temperature is between 32 to +113 °F (0 and +45 °C).
Check the rotation direction of the blowers after the electrical connections have been made (see
rotational direction arrow).
Clean the drying hoppers before filling them for the first time.
Follow the material manufacturers’ instructions for maximum drying temperature.
Follow the material manufacturers’ drying instructions.
Ensure that the drying hoppers are always completely filled and that the retention period is
respected if material is continually being removed.
Note that if too much material is taken from the drying hopper, it will lead to insufficient drying of
the material.
Close the air stop valves of the drying hoppers which are empty or have not been used.
Write down all data which you have entered into the control system.
The password is to be given to authorized personnel only.
Please note that the temperature of the dryer heating system must always be set lower than that
of the supplementary heaters.
When you dispose of drying agents, observe all official rules and guidelines.
Note that drying cells should be replaced or refilled only by Sterling if they are empty.
When no material is continuously fed into the drying hopper (batch drying) and is continuously
removed, the material level must not fall below 40% in the drying hopper. Close the throttle
valves.
Read the operating manuals of any machines connected to this dryer.
Safety instructions 2-5
STT40 / STT70
3. Start up
This chapter is addressed to the operators of the machine.
It assumes the operator has general skills with drying equipment
and that the functional description has been read and
understood.
Ensure that the operators have the required experience.
) Make sure that the main switch is set to the “0" position.
Check the drying hopper for cleanliness.
Check to see whether the adhesive film on the drying hopper has
been removed.
If there is a return air cooler, switch on the coolant circuit.
If there is a timer clock (optional), adjust it. Read the timer clock
operating manual.
Check whether the release switches for the “Timer” and the
“Hopper” (ST1, ST2) are set to the ”0" position.
The “trouble” signal lamp may flash shortly while the valve block
is being changed.
Start up 3-1
STT40 / STT70
3.1. Initial Operation
Check whether the inlet of the drying hopper is closed by a lid or whether a conveyor unit
(optional) is installed.
If not, manufacture a suitable lid and install it on the inlet of the drying hopper or install the
optional conveyor unit.
) Attachments which are not supplied by Sterling must be
manufactured according to the European Standard 294 safety
regulation.
Check whether the coolant circuit of the return air cooler (if a return air cooler is installed) is
turned on.
3.1.1. Switching on the Dryer
1. Turn on the dryers’ main power switch.
The “run” signal lamp lights up.
2. For operation with timer clock (optional):
Turn the “Timer” switch to the ON position:
For operation without timer clock:
Turn the “Timer” switch to the ON position:
The blower is running.
) If the dryer has not been used for several months it must be run
for 2 hours without material.
Start up 3-2
Turn the “Hopper” release switches (ST1, ST2) to the “I” position.
To set the drying temperature, turn the temperature controller to 176° F (+80 °C).
Press the “PGM” key one time.
Set the drying temperature to 176° F using the arrow keys.
After 2 seconds, the display will flash and the value will be stored.
Press the “EXIT” key (the setpoint value and the actual value
of the drying temperature are displayed).
After 2 hours, turn the “Hopper” release switches (ST1, ST2) to the “0” position.
Turn the “Timer” switch to the OFF position:
/ Wait until the blower has stopped.
The blower will continue running for 10 minutes once it is turned
off.
STT40 / STT70
If there is a return air cooler installed, turn off the coolant circuit.
Turn off the dryers’ main power switch.
The “power” signal lamp turns off.
Note: The previous steps only need to be taken if this is the initial
startup of the dryer, or if the dryer has been sitting for
several months.
Start up 3-3
3.2. Continuous Operation
Note: To see a quick start guide for operation of this dryer see
chapter 14.
) Fill at least half of the drying hopper with material.
3.2.1. Switching the Dryer on
Turn on the dryers’ main power switch to the on position.
The “run” signal lamp turns on.
For operation with the optional timer clock:
Turn the “Timer” switch to the position.
STT40 / STT70
For operation without timer clock:
Turn the “Timer” switch to the position.
The blower is running at this point.
Start up 3-4
STT40 / STT70
3.2.2. Setting the Drying Temperature
Turn the “Hopper” (ST1, ST2) release switches to the “I” position.
For each drying hopper, set the required process drying temperature by using the corresponding
temperature controller.
Check whether the set process drying temperature is appropriate for the materials which have
been placed in the drying hopper.
Observe the instructions of the material manufacturer.
After filling the drying hopper you must wait for the resonance time of the material to pass before
using the material for making product.
Observe the instructions of the material manufacturer.
Use the following steps to set the temperature controller.
Press the “PGM” key.
By using the arrow keys, select the desired value for
the drying temperature.
After 2 seconds, the display will flash and the value is stored.
Press the “EXIT” key (the setpoint value and the actual value
of the drying temperature are displayed).
) After changing materials, immediately check and reset the drying
temperature.
Start up 3-5
Autotuning the temperature controller
Press the “EXIT” key for at least 2 seconds.
“tunE” flashes. Autotuning can take several minutes.
If “tunE” stops flashing, Autotuning is finished.
Press the “EXIT” key.
STT40 / STT70
Start up 3-6
3.3. Switching the Dryer off
Turn the “Timer” switch to the position:
/ Wait until the blower has stopped.
The blower will continue running for 10 minutes once the dryer is
turned off.
If there is a return air cooler installed, switch off its coolant circuit.
Turn off the dryer’s main power switch.
The “power” signal lamp turns off.
STT40 / STT70
Note:
For more detailed instructions on the shutting down of this
dryer, see the quick start guide in Chapter 14.
Start up 3-7
STT40 / STT70
4. Error and error correction
This chapter is directed at the operators of the equipment.
It assumes the operator has general skills in dealing with drying
systems and that the “start-up” description has been read and
understood.
Ensure in each and every case that the operators have the
relevant skills in operating this equipment.
) Faults must be eliminated before the control system can start
operating again.
An alarm is indicated by the steady light of the “trouble” signal
lamp.
When the fault has been eliminated, the “trouble” signal lamp
turns off.
Error and error correction 4-1
The following errors can cause an alarm:
Blower
The blower pressure is too low.
Check the blower.
Vacuum sensor is defective.
Regeneration heater 1
The safety temperature limiter on regeneration heater 1 has been activated.
Check the safety temperature limiter.
Call the Sterling Service Department.
Regeneration heater 2
The safety temperature limiter on regeneration heater 2 has been activated.
Check the safety temperature limiter.
Call the Sterling Service Department.
Hopper heater
The safety temperature limiter on the hopper heater has been activated.
Check the safety temperature limiter.
Call the Sterling Service Department.
STT40 / STT70
Error and error correction 4-2
STT40 / STT70
5. Maintenance
This chapter is intended for persons having skills in electrical and
mechanical areas due to their training, experience and supporting
documentation.
Personnel using the instructions in this chapter must be familiar
with accident prevention regulations, operating conditions, safety
regulations and their implementation.
Ensure in each case that the personnel are informed.
For maintenance work taking place at heights of over 6ft.
(1829mm), use only ladders and working platforms or similar
equipment intended for this purpose. At greater heights, the
proper protective equipment against falling must be worn.
Use only suitable lifting gear in proper working order and load
suspension devices within the sufficient carrying capacity. Do not
stand or work under suspended loads!
Ensure that electric motors and controller cabinets are
sufficiently protected against moisture.
Use suitable workshop equipment.
Before starting maintenance work, appoint a supervisor.
Before beginning maintenance work on the system, inform the
responsible personnel.
Never operate the equipment when it is partially dismantled.
Any maintenance and repair work NOT described in this manual
may only be carried out by Sterling service personnel or by
specialized staff authorized by Sterling.
/ To ensure that it cannot be switched on unintentionally,
disconnect the equipment from the main power supply before
starting maintenance procedures.
Before starting maintenance work, all compressed air pipes on
the equipment should be depressurized.
Maintenance 5-1
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