AD-25, 30, 50, 75 and 758 Service Manual Phase 7.2 Non-Coin American Dryer Corporation 88 Currant Road Fall River MA 02720-4781 USA Telephone: (508) 678-9000 / Fax: (508) 678-9447 e-mail: techsupport@amdry.com www.amdry.com ADC Part No.
Retain This Manual in a Safe Place for Future Reference This product embodies advanced concepts in engineering, design, and safety. If this product is properly maintained, it will provide many years of safe, efficient, and trouble free operation. Only qualified technicians should service this equipment. OBSERVE ALL SAFETY PRECAUTIONS displayed on the equipment or specified in the installation manual included with the dryer.
IMPORTANT You must disconnect and lockout the electric supply and the gas supply or the steam supply before any covers or guards are removed from the machine to allow access for cleaning, adjusting, installation, or testing of any equipment per OSHA standards. Please observe all safety precautions displayed on the equipment and/or specified in the installation manual included with the dryer. CAUTION Dryer(s) should never be left unattended while in operation.
SECTION I IMPORTANT INFORMATION A. SAFETY PRECAUTIONS 1. DO NOT store or use gasoline or other flammable vapors and liquids in the vicinity of this or any appliance. 2. Purchaser and user should consult the local gas supplier for proper instructions to be followed in the event the user smells gas. The instructions should be posted in a prominent location. 3. Dryers must be exhausted to the outdoors. 4.
SECTION II ROUTINE MAINTENANCE A. CLEANING A program and/or schedule should be established for periodic inspection, cleaning, and removal of lint from various areas of the dryer, as well as throughout the ductwork system. The frequency of cleaning can best be determined from experience at each location. Maximum operating efficiency is dependent upon proper air circulation. The accumulation of lint can restrict this airflow.
MONTHS Inspect and remove lint accumulation in the customer furnished exhaust ductwork system. Inspect exhaust draft dampers to ensure they are not binding. Inspect and remove ALL lint accumulation from in and around control box area including coin acceptors. Clean lint accumulation from around tumbler wrapper area. IMPORTANT: THE ACCUMULATION OF LINT IN THE EXHAUST DUCTWORK CAN CREATE A POTENTIAL FIRE HAZARD. AS REQUIRED In the cleaning and care of the cabinet, avoid using harsh abrasives.
SECTION III INSTALLATION REQUIREMENTS Installation should be performed by competent technicians in accordance with local and state codes. In the absence of these codes, the installation must conform to applicable American National Standards: ANSI Z223.1-LATEST EDITION (National Fuel Gas Code) or ANSI/NFPA NO. 70-LATEST EDITION (National Electrical Code) or in Canada, the installation must conform to applicable Canadian Standards: CAN/CGA-B149.1-M91 (Natural Gas) or CAN/CGA-B149.2-M91 (Liquid Propane [L.P.
B. ELECTRICAL AND GAS REQUIREMENTS 1. Electrical Requirements It is your responsibility to have ALL electrical connections made by a properly licensed and competent electrician to assure that the electrical installation is adequate and conforms to local and state regulations or codes. In the absence of such codes, ALL electrical connections, materials, and workmanship must conform to the applicable requirements of the National Electrical Code ANSI/ NFPA NO.
C. OPERATIONAL SERVICE CHECK PROCEDURE After performing any service or maintenance function, an operational check should be performed to ensure that ALL components are performing properly. 1. Make a complete operational check of ALL the operating controls to assure that the timing is correct, temperature selection switches are functioning, etc. 2. Make a complete operational check of ALL safety related circuits, door switch(es), hi-limit thermostat, sail switch, cycling thermostats, etc. 3.
SECTION IV DESCRIPTION OF PARTS A. CONTROL PANEL (MICROPROCESSOR) Lifting the control door will reveal the control panel assembly. Opening the control panel will allow access to the major components, which include the computer board, and keypad. The keypad inputs to the computer what temperature and program has been selected. The computer controls the entire operation of the dryer. It accepts inputs and gives outputs to various parts throughout the dryer. B.
D. LINT DRAWER SWITCH The lint drawer switch is located in the lint compartment and attached to the side of the lint drawer track. The lint drawer switch ensures that the dryer will operate only when the lint drawer is completely close. This is a safety device and should never be disabled. E. LINT DRAWER The lint drawer is a pullout type and is located at the bottom of the dryer in the lint compartment.
G. TUMBLER BEARING AND PULLEY ARRANGEMENT The tumbler bearing and the pulley arrangement is located (viewing from the rear of the dryer) approximately at the upper center of the dryer. The arrangement consists of a pulley, bearing platform, and bearing, which serve to adjust, drive, and support the tumbler. H. IDLER BEARING Viewing from the rear of the dryer, the idler assembly is located approximately on the lower left hand side of the dryer. The idler assembly consists of one (1) compound pulley.
J. TEMPERATURE SENSOR (COMPUTER CONTROLS) The temperature sensor used, is a transducer that converts heat into microamps that the computer board then uses to calculate the temperature. K. GAS BURNER Gas dryers are equipped with a gas burner located behind the control door. The gas burner assembly consists of the burner tubes, orifices (the orifices have a hole in them to allow gas to flow through.
M. COMPRESSED AIR REQUIREMENTS This dryer requires an external supply of air (2.5 cfm @ 80 psi [0.07 cmm @ 5.51 bar]) on the steam models, the air is necessary to operate the steam damper system. On both steam, as well as the gas model, the air is necessary for the blower air jet operation to clean lint from the impellor/fan (squirrel cage type). N. ELECTRIC OVEN Electric dryers are equipped with an electric oven located behind the control door.
P. MOTOR CONTACTOR (1Ø MOTOR) This motor contactor used on a single-phase (1ø) dryer, is located in the rear of the dryer, in the electrical panel box. Its purpose is to transfer the higher voltage to the motor, when the contactor coil voltage has been achieved. Q. NON-REVERSING CONTACTOR (3Ø MOTOR) The non-reversing contactor is used on 3-phase (3ø) non-reversing dryers and is located on the upper left hand side of the dryer (view from the rear).
S. HI-LIMIT THERMOSTAT (GAS AND ELECTRIC MODELS ONLY) The hi-limit thermostat is another safety device that we use on gas and electric models. The hi-limit is located in the burner or oven area. The hi-limit switch cuts off the heat, if the temperature exceeds 290° for electric models or 330º for gas models. The only way this device would shut off the heat, is when the airflow changes to the extent of making the flame brush up against it. 16 American Dryer Corp.
SECTION V SERVICING IMPORTANT: YOU MUST DISCONNECT AND LOCKOUT THE ELECTRIC SUPPLY AND THE GAS SUPPLY BEFORE ANY COVERS OR GUARDS ARE REMOVED FROM THE MACHINE TO ALLOW ACCESS FOR CLEANING, ADJUSTING, INSTALLATION, OR TESTING OF ANY EQUIPMENT PER OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION (OSHA) STANDARDS. WARNING: PERSONAL INJURY COULD RESULT. The information provided in this section should not be misconstrued as a device for use by untrained persons making repairs.
TO REPLACE COMPUTER 1. Discontinue power to the dryer. 2. Disconnect the J3, J4, J5, J6, and J8 harnesses from the rear of the computer by squeezing the top locking tab and pulling the connector straight back. 3. Disconnect the green ground wire from the computer. 4. Disconnect the keypad ribbon from the computer. 5. Remove the two (2) screws securing the computer to the control panel and remove computer from the panel, by pulling upwards on the corners. 6.
TO REPLACE COMPUTER TEMPERATURE SENSOR PROBE 1. Discontinue power to the dryer. 2. Remove microprocessor sensor bracket assembly from the dryer. a. Disconnect sensor bracket harness connector. b. Loosen the two (2) Phillips head screws securing the bracket assembly to the dryer and remove the bracket from the dryer. NOTE: DO NOT remove screws. 3. Disassemble the sensor probe from the bracket assembly by removing the top push on fastener securing the probe to the bracket.
B. BURNER CONTROLS (GAS) This illustration is typical of ALL gas burners, but they are not ALL exactly alike. Your particular model may have some differences. TO REPLACE SPARK IGNITOR 1. Discontinue power to the dryer. 2. Disconnect high voltage connector and flame-probe connection from ignitor. 3. Disassemble ignitor from burner by removing the two (2) self-tapping screws. 4. Reverse procedure for installing the new ignitor probe.
TO REPLACE GAS VALVE 1. Discontinue power to the dryer. 2. Close shutoff valve in the gas supply line. 3. Disconnect the gas valve wiring. 4. Break union connection before gas valve. 5. Loosen and remove two (2) screws securing pipe bracket to the burner. 6. Remove gas valve/manifold assembly from the dryer. 7. Remove manifold from outlet of the gas valve. 8. Remove union tailpiece from valve. Use a 1/2” Allen wrench (ADC Part No. 410001). 9. Reverse procedure for installing the new gas valve.
NOTE: Manometers are available from the factory by ordering ADC Part No. 122804. 1. To test gas water column (W.C.) pressure. a. Connect water column test gauge connection to gas valve pressure tap (1/8” N.P.T). This pressure tap is located on the outlet (downstream) side of the valve. b. Start the dryer. With burner on, the correct water column reading in inches would be: Natural Gas __________________ 3.5 Inches (8.7 mb) Water Column Liquid Propane (L.P.) Gas _______ 10.5 Inches (26.1 mb) Water Column 2.
TO CONVERT FROM NATURAL TO LIQUID PROPANE (L.P.) GAS 1. Disconnect electrical power to the dryer. 2. Close ALL shutoff valves in dryer gas supply line. 3. Disconnect gas valve wiring. NOTE: Identify location of each wire for correct reinstallation. 4. Break union connection (nut) between union shutoff and gas valve. 5. Loosen and remove screws from bracket holding the gas valve/manifold assembly to burner box. 6. Remove gas valve/manifold assembly from the dryer. 7.
TO REPLACE BURNER TUBES 1. Discontinue power to the dryer. 2. Close shutoff valve in the gas supply line. 3. Disconnect the gas valve wiring. 4. Break union connection before gas valve. 5. Loosen and remove two (2) screws securing the gas valve bracket to the burner. 6. Remove gas valve/manifold assembly from the dryer. 7. Remove the screws securing the front flanges of the burner tubes to the burner rest. 8. Remove burner tubes by sliding them out. 9. Replace by reversing procedure.
C. STEAM CONTROLS INSTALLATION Piping must be installed in accordance with good commercial steam system practice. Refer to the illustration below for a typical pipe arrangement. STEAM DAMPER SYSTEM MAN0582 450268-1 www.amdry.
TO REPLACE STEAM COIL (DAMPER SYSTEM) 1. Discontinue power to the dryer. 2. Remove the four (4) lock washers and hex nuts securing the hinges to the steam coil. 3. Remove hinges from the steam coil housing (these will be used on the new assembly). 4. Remove six (6) washers and hex nuts securing steam coil to the dryer. 5. Remove the steam coil assembly. 6. Reverse procedure for the new steam coil assembly. TO REPLACE PISTON 1. Discontinue power to the dryer. 2. Discontinue the air supply to the dryer. 3.
TO REPLACE THE NEEDLE VALVE 1. Discontinue power to the dryer. 2. Discontinue the air to the dryer. 3. Remove the 1/8” brass close nipple from the needle valve. 4. Remove the 1/8” M.P.T. connector from the needle valve. 5. Remove the needle valve. 6. Reverse procedure to install the new needle valve. TO REPLACE THE 3-WAY MICROVALVE 1. Discontinue power to the dryer. 2. Discontinue the air to the dryer. 3. Remove inlet side of air from the 3-way valve. 4.
D. ELECTRICAL OVEN CONTROLS TO REPLACE ELECTRICAL ELEMENTS 1. Discontinue power to the dryer. 2. Remove cover by removing two (2) screws and lifting the cover. 3. Remove the screws and wiring holding the element in place at the rear of the oven. 4. From the front of the oven, slide out element. 5. Reverse procedure for installation of new element. TO REPLACE OVEN CONTACTOR 1. Discontinue power to the dryer. 2. Remove wiring from contactor. 3. Remove three (3) nuts and lug nuts from the studs. 4.
E. THERMOSTATS AND TEMPERATURE SENSOR TO REPLACE HI-LIMIT THERMOSTAT (330º GAS, 290º ELECTRIC) This thermostat is an important safety device serving as an added protection against failure of the air sail switch to open in the event of motor failure or reduced airflow condition. IMPORTANT: UNDER NO CIRCUMSTANCES should heat circuit safety devices ever be disabled. 1. Discontinue power to the dryer. 2. Disconnect wires from hi-limit thermostat. 3.
2. Temperature Sensor (Microprocessor Models) a. Discontinue power to the dryer. b. Open and remove the lint door. c. Disconnect sensor bracket harness connector. d. Loosen the two (2) Phillips head screws securing bracket assembly to dryer and remove by sliding bracket towards the rear of the dryer. e. Disassemble sensor probe from bracket assembly by removing the top push on fastener securing the probe to the tumbler. f. Disconnect the two (2) orange wires from the high heat temperature thermostat.
TO ADJUST SAIL SWITCH 1. Operate the installed dryer normally to verify that the heat system is fully operational. 2. Open the main dryer door. 3. Manually depress the door switch actuator. 4. While continuing to depress the door switch actuator, and with the door open, start the dryer. 5. If the heat system is not activated in 15-seconds, the sail switch is properly adjusted. 6.
TO REPLACE MAIN DOOR ASSEMBLY 1. Remove screws holding main door to main door hinge. 2. Reverse this procedure for reinstalling the new main door assembly. TO INSTALL NEW MAIN DOOR GLASS 1. Remove main door assembly from the dryer (follow main door removal procedure). 2. Lay main door on a flat surface with front of door face down. 3. Remove glass and clean ALL old sealant off main door. This area must be completely cleaned for correct bonding. 4. Apply narrow bead of silicone (ADC Part No.
5. Remove the screws securing the front panel to the dryer. 6. Gently remove the top right hand corner of the front panel assembly from the dryer. 7. Disconnect the main door switch harness at the connector. IMPORTANT: When removing front panel assembly, be careful not to damage main door switch wires disconnected in Step #2. 8. Reverse this procedure for installing the new front panel. TO REPLACE MAIN DOOR HINGE 1. Discontinue power to the dryer. 2. Follow procedure for removal of the main door assembly.
H. TUMBLER AND BEARING ASSEMBLY (Remove back guard to access assembly) TO REPLACE TUMBLER PULLEY (NON-REVERSING) 1. Loosen V-belts, then rotate pulley and roll V-belts out of the grooves. 2. Loosen two (2) setscrews on the pulley and pull the pulley off the shaft. 3. Reverse procedure for installing the new tumbler pulley. NOTE: Check belt alignment before operating the dryer. TO REPLACE TUMBLER PULLEY (REVERSING) 1. Loosen V-belts, then rotate pulley and roll V-belts out of the grooves. 2.
TO REPLACE THE REAR TUMBLER BEARING 1. Remove the tumbler pulley (follow tumbler pulley removal procedure). 2. Remove the four (4) bolts securing the bearing platform to the back of the dryer. 3. Loosen Allen screw securing bearing collar to the shaft. 4. Slide bearing collar off the tumbler support. 5. Pull bearing platform and bearing housing off of shaft. NOTE: If any rust has developed, use an emery cloth to polish the shaft. 6.
I. IDLER AND BEARING ASSEMBLY (Remove back guard to access assembly) TO REPLACE IDLER PULLEY 1. Remove the back guard. 2. Loosen V-belts, then rotate pulley and roll V-belts out of the grooves. 3. Loosen the two (2) setscrews on the pulley and pull off the shaft. 4. Reverse procedure for installing the new idler pulley. NOTE: Check tension and alignment of belts before operating the dryer. TO REPLACE IDLER BEARING 1. Remove the idler pulley (follow “TO REPLACE IDLER PULLEY”). 2. Remove the idler arm. a.
J. DRIVE PULLEY (Remove back guard to access assembly) 1. Remove the back guard. 2. Loosen V-belts then rotate pulley and roll V-belts out of the grooves. 3. Loosen setscrews and pull motor pulley out. NOTE: If rust has developed on the shaft, use an emery cloth to polish the shaft. 4. Reverse procedure for installing the new drive pulley. NOTE: Check tension and alignment of belts before operating the dryer. K. TUMBLER TUMBLER ALIGNMENT (VERTICAL) 1. Discontinue power to the dryer. 2.
TUMBLER ALIGNMENT (LATERAL) 1. Discontinue power to the dryer. 2. Remove the back guard. 3. Loosen the two (2) hex head bolts, (one [1] turn is enough), that holds the pillow block bearing to the bearing box. 4. Back off the two (2) jam nuts on the side adjustment bolts. Now, rotate the tumbler from the front of the dryer, checking the space between the tumbler and the front panel. This should be equal on the left hand and right hand side. 5. Lateral adjustment (viewing from the rear). a.
TO REPLACE THE TUMBLER AND/OR TUMBLER SUPPORT 1. Discontinue power to the dryer. 2. Remove the tumbler pulley. 3. Remove the front panel assembly. a. Open the control (service) door. b. Open the lint door. c. Remove the screws securing the front panel to the dryer. d. Gently remove the top right hand corner of the front panel assembly from the dryer. e. Disconnect the main door switch harness at connector. IMPORTANT: When removing the front panel assembly, be careful not to damage the door switch wires. 4.
L. V-BELTS (Refer to illustration in Sections I, J, and K) V-belts should have proper tension. If too loose, they will slip, if too tight excessive wear on the bearing will result. If the pulleys are not properly aligned, excessive belt wear will result. Proper belt tension will allow 1/2” displacement under normal thumb pressure at mid span of the belt. V-BELT TENSION ADJUSTMENT – TUMBLER TO IDLER 1. Loosen two (2) bolts connecting idler arm to backup plate. 2. Back off jam nut on the adjustment bolt. 3.
TO REPLACE V-BELTS 1. Loosen tension on V-belts, so that they can easily be rolled off pulleys. 2. Replace V-belts. 3. Retighten V-belts and adjust tension and alignment per previous instructions. M. MOTOR TO REPLACE MOTOR (NON-REVERSING) 1. Discontinue power to the dryer. 2. Remove the drive belt. 3. Disconnect wiring harness from the motor. 4. Remove nuts and washers holding the motor mount to the rear of the dryer and pull motor mount away. 5.
O. LINT DRAWER SCREEN TO REPLACE LINT SCREEN 1. Gently slide the lint drawer outward. 2. Remove the lint bag and inspect for rips or tears. Replace with new lint bag, if damaged. 3. Reverse procedure for installing the new lint bag. 4. Close the lint drawer. 42 American Dryer Corp.
SECTION VI TROUBLESHOOTING The information provided will help isolate the most probable components associated with the difficulty described. The experienced technician realizes, however, that a loose connection or broken or shorted wire may be at fault where electrical components are concerned...not necessarily the suspect component itself. Electrical parts should always be checked for failure before being returned to the factory.
PHASE 7 NON-COIN SYSTEM DIAGNOSTICS IMPORTANT: YOU MUST DISCONNECT AND LOCKOUT THE ELECTRIC SUPPLY AND THE GAS SUPPLY OR THE STEAM SUPPLY BEFORE ANY COVERS OR GUARDS ARE REMOVED FROM THE MACHINE TO ALLOW ACCESS FOR CLEANING, ADJUSTING, INSTALLATION, OR TESTING OF ANY EQUIPMENT PER OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION (OSHA) STANDARDS. ALL major circuits, including door, microprocessor temperature sensor, heat and motor circuits are monitored.
BURNER PURGE FAULT – The gas valve signal is present during the prepurge time. MODEL ERROR, ENTER CORRECT MODEL – The wrong model was selected for the dryer. EE PROM FAULT ### – Error in memory location. The ### indicates the location of the fault. B. INPUT/OUTPUT BOARD LIGHT EMITTING DIODE (L.E.D.) INDICATORS 1. Inputs (Red L.E.D.) 1. ESTOP – This L.E.D. will indicate the status of the E-STOP. If the E-STOP has been pressed, then the L.E.D. is on. 2. GAS_V – This L.E.D.
2. Outputs (Green L.E.D.) 9. AUX – This is for a spare output to be programmed. 10. STEAM – This light emitting diode (L.E.D.) will indicate the status of the steam injection output. If the request to turn on the steam injection is made, then the L.E.D. is ON. 11. _HEAT – This L.E.D. will indicate the status of the heat output. If the request to turn on the heater is made, then the L.E.D. is ON. 12. AIR – This L.E.D. will indicate the status of the air jet output.
A. The display reads “Exhaust High Limit Fault”. (Refer to page 51) The temperature in the tumbler is above 220º F (104º C) or follow Steps #1 through #4. 1. Check for voltage (24 VAC) at the computer on the J5 connector from pin 1 to ground. If no voltage is present, either you have a poor connection at the J5 connector or the computer board is faulty. If voltage (24 VAC) is present, proceed to Step #2. 2. Check for voltage (24 VAC) at the J12 connector pin 3 to ground.
E. The display reads “Sail Switch Closed Fault”. (Refer to page 52) 1. Prior to start up, the sail switch is in the closed position. 2. Check the sail switch and readjust accordingly. 3. Replace sail switch, if necessary. F. The display reads “Burner Ignition Control Fault”. (Refer to page 52) 1. Check for 24 VAC at the Direct Spark Ignition (DSI) module across MV and GND. If no voltage, replace the DSI module. If voltage is present, check for 24 VAC at the gas valve on terminals 1 and 2.
H. Drive motor reverses, but does not go forward, blower motor runs. The display reads “Rotation Fault”.* (Refer to page 57) 1. Possible causes: a. Belt is broke, loose, or slipping. b. Lint accumulation on the rotational sensor. c. Rotational sensor magnet is missing or broke. Reset power, then, restart the dryer. d. Check for 24 VAC at the computer board J8 connector pin 8 brown wire to GND. If no voltage is present, check for a loose connection, if connection is good, replace computer.
J. No display condition or display reads “Low Voltage Fault”.* (Refer to page 54) 1. Check for line voltage (120, 208, 240, etc.) in the rear of the dryer at the distribution block. If no voltage is present, the problem may be a faulty or tripped breaker. If voltage is present, check for line voltage (120, 208, 240, etc.) at FIA (refer to illustration on page 54) to neutral. If no voltage is present, check for blown fuse or loose connection. 2.
450268-1 www.amdry.
American Dryer Corp.
450268-1 www.amdry.
American Dryer Corp.
450268-1 www.amdry.
American Dryer Corp.
450268-1 www.amdry.
SECTION VII DATA LABEL INFORMATION A. DATA LABEL When contacting ADC, certain information is required to ensure proper service/parts information from ADC. This information is on the data label affixed to the left side panel/wall area behind the control door. When contacting ADC, please have the model number and serial number available. 1. MODEL NUMBER – Describes the size of the dryer and the type of heat (gas, electric, or steam). 2.
B. USING A MANOMETER HOW TO USE A MANOMETER 1. With dryer in nonoperating mode, remove plug on the gas valve pressure tap. 2. Install 1/8” N.P.T. fitting supplied with the manometer. 3. Attach plastic tubing to pressure tap fitting. 4. Attach manometer to dryer using magnet. NOTE: Place manometer in a position so that readings can be taken at eye level. 5. Fill manometer as shown in illustration to the zero level. 6. Start dryer. With burner on take a reading. a. Read water level at the inner tube.
C. KEYPAD LAYOUT 1. Dot Matrix Display 2. A-F Preprogrammed Cycles 3. Stop/Pause Button 4. Start Button 5. Increment Button 6. Decrement Button 7. One time Auto (Dryness level) and Manual (Timed) Cycle NOTE: Fuse 1 is for computer power rated at 1/2-Amp. If fuse blows, it is a computer board fault. Fuse 2 is for 24V control power rated at 5-Amp. If fuse blows, it is a 24V control fault. 60 American Dryer Corp.
D. SENSOR ACTIVATED FIRE EXTINGUISHING (S.A.F.E.) SYSTEM THEORY OF OPERATION While the dryer is in an idle state or 20-seconds after the heat turns off, the Phase 7 control monitors the S.A.F.E. system probe located in the top of the tumbler chamber and records the minimum temperature. If the minimum recorded S.A.F.E. system probe temperature is no less than 120° F (48° C) and the control detects a 50° rise in temperature, this will be the trip point and the S.A.F.E. system routine will activate.
E. STATIC PRESSURE The pressure of the air in sheet metal ducts is of great importance for safe and efficient operation of the dryer. The air pressures, as small as they are, have a large influence upon the performance of the dryer. There are three (3) pressures present within a duct.
F. USING A MAGNEHELIC When measuring such small air pressures, the U-tube is often not accurate enough. Such small differences in pressure are most often measured by an inclined tube manometer or a Magnehelic pressure gage as shown in Illustration #2. ILLUS. #2 For convenience and accuracy, an instrument known as a Pitot tube is used with the gage. The Pitot tube, as shown in Illustration #3, consists of two tubes – one within the other.
To obtain the most accurate static pressure readings of a dryer, the following guidelines should be conformed to. The reading should be taken in a straight section of duct, a minimum of ten (10) times the diameter of the duct (i.e. 10-inches [25.4 cm] diameter duct, a straight section 100-inches [254 cm] in length). The reading should be taken a minimum of 8-1/2 times the diameter upstream of the dryer or nearest elbow, and 1-1/2 times the diameter downstream of the Pitot tube.
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ADC Part No.