Honeywell MP904A5047 / MP904A5047-3 Pneumatic Damper Operator

The Honeywell MP904A & MP904B Pneumatic Damper Operators regulate airflow in heating, cooling, and ventilation systems. These actuators use air pressure for proportional or two-position control, ensuring precise damper blade positioning.

Key Features

Rolling Diaphragm Operation – Enhances reliability and durability.
Universal Mounting Bracket – Supports internal installation for Honeywell Moduflow® dampers or external installation on all damper types.
Optional Positive Positioner – Provides accurate positioning under varying load conditions.

Specifications

Model Variants

MP904A – Standard operator with positioner.
MP904B – Standard operator without positioner.

Operating Parameters

Specification	MP904A	MP904B
Max. Safe Air Pressure	25 lb/in² (172 kPa)	25 lb/in² (172 kPa)
Start Point Pressure	Adjustable 3-10 lb/in² (20-70 kPa)	Factory set at 2, 3, or 7 lb/in² (15, 20, or 50 kPa)
Operating Range	See Tables 1 & 2	See Tables 1 & 2
Damper Load Rating	See Tables 1 & 2	See Tables 1 & 2

Force Exerted (Including Tolerances)

Pressure	MP904A	MP904B (2-7 lb/in²)	MP904B (3-13 lb/in²)	MP904B (7-13 lb/in²)
0 lb/in² (0 kPa)	150 lb (68 kg)	40 lb (18 kg)	62 lb (28 kg)	150 lb (68 kg)
18 lb/in² (125 kPa)	90 lb (41 kg), 140 lb (64 kg)	250 lb (103 kg)	100 lb (45 kg)	90 lb (41 kg)

Stroke & Adjustment

Stroke Type	MP904A & MP904B (3-13 lb/in²)	MP904B (2-7 lb/in²)	MP904B (7-13 lb/in²)
Factory Set Stroke	3.5 in. (89 mm)	3.5 in. (89 mm) (Adjustable: 2-3.5 in.)	3 in. (76 mm) (Adjustable: 2-3.5 in.)
Stroke Stop Kits	Available separately	Included	Included

Optional Stroke Start Adjustment – Increases stroke start point by up to 1/2 in. (13 mm).
Stroke Stop Kit – Reduces full stroke travel up to 1.25 in. (32 mm) for 2-7 lb/in² range and 0.75 in. (19 mm) for 7-13 lb/in² range.

Environmental & Material Specifications

Parameter	Value
Ambient Temperature Range	-20 to 160°F (-29 to 71°C)
Air Connection	1/8″ NPT female (with factory-installed push-on connector for 5/32″ and 1/4″ OD plastic tubing)
Finish	Cast aluminum & stainless steel
Diaphragm	Neoprene, rolling type
Dimensions (Excluding Bracket)	Length: 8-7/8 in. (225 mm), Diameter: 6-1/4 in. (159 mm)
Mounting	Bracket & screws provided

Accessories

Linkage for External Mounting – Connects 1/2″ (13 mm) OD shaft (Part No. 14002061-001).
Stroke Start Adjustment Nuts – Two required (Part No. 304662).
Stroke Stop Adjustment Kit – (Part No. 314959A).
Crank Arm for 3/8″ (9 mm) Shaft – (Part No. 26025B).
Crank Arm Ball Joint – (Part No. 315321-00062).
Additional Accessories – See Form No. 74-5413 for MP909A-D Operator Accessories.

Ordering Information

When ordering, specify:
✔ Model Number
✔ Mounting Type (Internal or External)
✔ Pressure Range
✔ Accessories Needed

Typical Operation

MP904A – Sequential Damper Control

Used with direct-acting controllers to control damper sections in sequence.
An increase in temperature at LP914 increases branch line pressure, causing damper M2 to fully actuate before M1 starts moving.
Provides accurate damper positioning under varying load conditions.

MP904B – Central Fan System Operation

Works with manual-positioning switch (S1) and electric-pneumatic relay (R1).
Turning fan ON supplies pressure to the operator, opening the damper to a pre-set position.
When used with MP904A, ensure MP904B operates at 7-13 lb/in² range for compatibility.

The Honeywell MP904A & MP904B Pneumatic Damper Operators provide precise and reliable airflow control, making them ideal for HVAC, industrial ventilation, and environmental management applications.