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Honeywell L91A Product Data

Proportioning pressuretrol controllers.
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L91A,B,D Proportioning
Pressuretrol

APPLICATION

L91 Proportioning Pressuretrol
Modulating Pressure Controllers that provide direct control of
modulating motors or valves used on automatic burners or
steam heating systems.
®
Controllers
®
Controllers are Series 90

FEATURES

• Models available for pressure systems up to 300 psi
(2068 kPa).
• May be used with steam, air, noncombustible gases, or
other fluids noncorrosive to brass or phos-bronze (300
psi model) bellows.
• When used with steam boilers, a steam trap (siphon
loop) is recommended.
• Wiper on controller potentiometer moves in response
to pressure changes.
• L91D has two potentiometers for unison control of two
motors.
• L91B,D models have adjustable proportioning
(throttling) range to allow selection of desired
pressure control range.
• Adjustments made with screws on case top.
• Large, easily-read scaleplates in both U.S. customary
(oz/sq. in., psi, or in. Hg) and metric (kPa, MPa, or mm
Hg) units.
• Steel case with clear plastic cover to observe pressure
settings and potentiometer action.
• Fitting with 1/4 -18 NPT threads allows rapid
installation.
• Surface mount with screws through knockout holes in
case back.
PRODUCT DATA
Contents
1
1
2
5
6
8
9
Put UPC Code Here
60-2152-08

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Table of Contents

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   Summary of Contents for Honeywell L91A

  • Page 1: Table Of Contents

    L91A,B,D Proportioning ® Pressuretrol Controllers PRODUCT DATA FEATURES • Models available for pressure systems up to 300 psi (2068 kPa). • May be used with steam, air, noncombustible gases, or other fluids noncorrosive to brass or phos-bronze (300 psi model) bellows.
  • Page 2: Specifications

    If you have additional questions, need further information, or would like to comment on our products or services, please write or phone: 1. Your local Honeywell Automation and Control Products Sales Office (check white pages of your phone directory). 2. Honeywell Customer Care...
  • Page 3 129178 Thermoplastic Cover. 4074BWJ Limit Stop Assembly: To limit setpoint ranges; 23176CB Potentiometer: For all L91A models and a few L91B includes 129564 Range Stop 107194 Range Stop Screw, models (see Table 1); 140 ohms (nominal); length of active and 23466 Wrench.
  • Page 4 ® L91A,B,D PROPORTIONING PRESSURETROL CONTROLLERS 4-1/2 (114.3) (COVER) L91A,B,D (110.3) (CASE) 4-11/32 2-3/4 (69.9) 3-57/64 (98.8) 3-13/32 (86.5) 1-3/16 (30.2) 1-5/32 (29.4) 1-1/16 (27.0) 3-23/32 1-3/32 (27.8) (94.5) 3-7/8 2-5/64 (98.4) (52.8) ALL OTHER DIM C (SEE MODELS 1-13/16 TABULATION (22.2)
  • Page 5: Installation

    ® L91A,B,D PROPORTIONING PRESSURETROL CONTROLLERS INSTALLATION When Installing This Product... 1. Read these instructions carefully. Failure to follow them PRESSURETROL could damage the product or cause a hazardous CONTROLLER condition. 2. Check the ratings given in the instructions and on the...
  • Page 6: Wiring

    Setting In all models, the proportioning range (also called throttling range) extends above the main scale setpoint (Fig. 5). The proportioning range is fixed on L91A models, but is adjustable FRONT POTENTIOMETER L91D on L91B,D models. (For values, refer to Table 1 in the Specifications section.)
  • Page 7 W. This unbalances the circuit, so a larger current flows through one side of the balancing relay. The FIXED ON L91A; ADJUSTABLE ON L91B,D. close contacts in the relay make, causing the motor (or valve actuator) to drive toward its closed position. As the motor (or L91D HAS TWO POTENTIOMETERS OPERATING IN UNISION.
  • Page 8: Checkout

    KNURLED ADJUSTMENT KNOB ON 10 TO 300 PSI [0.07 TO 2.07 MPA] sured in step 4 (135 ohms for an L91A,B, or D). MODELS. 6. Slowly lowering the setpoint of the controller while TERMINALS ARE LABELED observing the ohmmeter reading.
  • Page 9: Service Information

    ® L91A,B,D PROPORTIONING PRESSURETROL CONTROLLERS SERVICE INFORMATION Replacing the Controller Potentiometer (Fig. 8–10) CAUTION IMPORTANT: 1. Replace the controller potentiometer only when nec- Electrical Shock Hazard essary to obtain proper operation. 1. Only qualified service technicians should attempt to 2. When replacing the potentiometer, be very careful not...
  • Page 10 MAIN DIFF. TERMINAL BLOCK DIFF. IS ADDITIVE POTENTIOMETER WIRES THE POTENTIOMETER IN AN L91A IS MOUNTED AT A 45 DEGREE ANGLE INSTEAD OF HORIZONTALLY. AN L91D HAS TWO POTENTIOMETERS. TERMINALS ARE LABELED. M8547A Fig. 9. Replacing potentiometer in L91. 60-2152—08...
  • Page 11 ® L91A,B,D PROPORTIONING PRESSURETROL CONTROLLERS 60-2152—08...
  • Page 12 Automation and Control Solutions Honeywell International Inc. 1985 Douglas Drive North Golden Valley, MN 55422 Honeywell Limited-Honeywell Limitée 35 Dynamic Drive ® U.S. Registered Trademark Toronto, Ontario M1V 4Z9 © 2009 Honeywell International Inc. 60-2152-—08 K.K. Rev. 12-09 customer.honeywell.com Printed in U.S.A.

This manual is also suitable for:

L91bL91d

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