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D770-24-00 

1 I56-1452-004R

WFDEXP Explosion Proof    

Vane-type Waterflow Detectors

INSTALLATION AND MAINTENANCE INSTRUCTIONS

Important

Please Read Carefully And Save

This instruction manual contains important information about the instal-
lation and operation of waterflow detectors. Purchasers who install 
waterflow detectors for use by others must leave this manual or a copy 
of it with the user.

Read all instructions carefully before beginning. Follow only those instruc-
tions that apply to the model you are installing.

CAUTION

Use vane-type waterflow detectors in wet-pipe systems only. Do NOT use 
them in dry pipe, deluge, or preaction systems. The sudden inrush of 
water in such systems may break the vane or damage the mechanism.

Principles of Operation

Vane-type waterflow detectors mount to water-filled pipes in sprinkler 
systems. Waterflow in the pipe deflects a vane, which produces a switched 
output–usually after a specified delay. All waterflow detectors have a 
pneumatically controlled mechanical delay mechanism. Delays do NOT 
accumulate; they reset if the flow of water stops before the entire delay 
has elapsed. All switches actuate when the water flow rate is 10 gallons 
per minute or greater, but will not actuate if the flow rate is less than 4 
gallons per minute. This System Sensor installation manual covers the fol-
lowing waterflow detectors for sprinkler/fire alarm applications.

   

 

Pipe 

Max. Pressure

 Model 

Pipe Size 

Schedule 

Rating (psig)

WFD20EXP 2

˝

 

10 thru 40 

450

WFD25EXP 2

1⁄2

˝

 

10 thru 40 

450

WFD30-2EXP 3

˝

 

10 thru 40 

450

WFD35EXP 3

1⁄2

˝

 

10 thru 40 

450

WFD40EXP 4

˝

 

10 thru 40 

450

WFD50EXP 5

˝

 

10 thru 40 

450

WFD60EXP 6

˝

 

10 thru 40 

450*

WFD80EXP 8

˝

 

10 thru 40 

450*

*Maximum Pressure Rating 400 psig as approved by Factory Mutual 
Research.

CAUTION

Do NOT use any of the WFD models on copper pipe. The clamping forces 
of the mounting bolts may collapse the pipe sufficiently to prevent the 
detector from functioning properly.
Do NOT install steel or iron pipe sections in copper piping for mounting a 
waterflow detector. Incompatibility between the dissimilar metals causes 
bimetallic corrosion.

Specifications

Contact Ratings: 

10 A @ 125/250 VAC 

; 2.5 A @ 24 VDC 

Triggering Threshold Bandwidth (Flow Rate): 

4 to 10 gpm

Static Pressure Rating: 

See models listed below

Dimensions, Installed: 

4.0

˝

H × 8.8

˝

W × 7.0

˝

D

Operating Temperature Range: 

32°F to 120°F (0°C to 49°C)

Compatible Pipe: 

Steel water pipe, schedule 10 or 40.

Shipping Weight: 

According to size.

Enclosure Rating: 

NEMA 4 indoor/outdoor use

 

Hazardous 

Atmosphere 

Classification: 

     

 

Class I, Groups B, C, D Div, 1; Class II, Groups E, F, G Div. 1; Class III Div. 1

US Patent Number: 

3,845,259; 4,782,333; 5,213,205

NOTE: 

  Not for use in potable water systems, systems where sand or 

other material is present or systems employing other than water.

Installation Guidelines

Before installing any waterflow alarm device, be thoroughly familiar 
with:

NFPA 72: 

National Fire Alarm Code

NFPA 13: 

Installation of Sprinkler Systems, Section 3.17

NFPA 25: 

Inspection, Testing and Maintenance of Sprinkler Systems, 
Section 5.3.3.2

Other applicable NFPA standards, local codes, and the requirements of the 
authority having jurisdiction

NOTE:

  Installation methods other than those listed in this installation 

manual may prevent the device from reporting the flow of water 
in the event the associated sprinkler system is activated by a 
fire. System Sensor is not responsible for devices that have been 
improperly installed, tested, or maintained.

1.  Mount the detector where there is adequate clearance for installation 

and removal and a clear view of it for inspections. See Figure 1 for 
mounting dimensions.

2.  Locate to protect from damage – 6 to 7 feet above the floor.
3.  On horizontal runs, position the detector on the top or side of the pipe. 

Do not mount it upside down because condensation may collect in 
the housing and impair the operation of the detector. For vertical flow 
applications, mount the detector on pipe through which water flows 
upward. Otherwise, the unit may not operate properly.

4.  Mount the detector at least 6 inches from a fitting that changes the 

direction of water flow and no less than 24 inches from a valve or 
drain.

5.  Be sure the direction-of-flow arrow matches the direction of flow in the 

pipe.

CAUTION

Contact the appropriate personnel regarding the proper tools and proce-
dures when installing this device in a “HAZARDOUS” area. Disconnect 
supply circuits before opening the cover, to reduce the chances of ignition 
of hazardous atmospheres. Secure the cover and cover screws prior to 
activating circuits. Tighten cover screws to 40 in. lbs. min.

6581  Kitimat Rd., Unit #6, Mississauga, Ontario, L5N 3T5

1-800-SENSOR2, FAX: 905-812-0771

www.systemsensor.ca

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