HomeMy WebLinkAbout405.010 - Flow Switch - Pressure SwitchEffective Date: March 2016 Justin H. Beal, Fire Prevention Engineer
Current Revision Date: 1/31/2025 Section 405.010
Next Revision (1) Date: 1/31/2028 Page 1 of 2
Fresno City Fire Department
400 Manual
SECTION 405.010 FLOW SWITCH / PRESSURE SWITCH
PURPOSE
The purpose of this policy is to clarify the Fresno Fire Department’s (FFD or
Department) requirements related to the required use of paddle type water flow
switches in lieu of pressure switches for all automatic fire sprinkler systems.
APPLICATION
This policy applies to all automatic fire sprinkler systems within the City of Fresno
(COF) and contract service areas and includes both required and voluntary systems.
OPERATIONAL POLICY
Based upon the need for uniformity in application across the Department’s diverse
service delivery area, and after careful deliberation, the Department has determined
that all, automatic fire sprinkler systems shall conform to the following requirements:
1. Pressure sensing waterflow switches shall not be permitted for indicating
water flow on all wet pipe, automatic fire sprinkler systems.
2. Alarm check valves with mechanical water motor gongs, vane or paddle type
water flow switches with electric bells, and similar, approved configurations
must be used for all local waterflow alarms for automatic fire sprinkler
systems.
3. Automatic fire sprinkler system monitoring must be accomplished by a vane or
paddle type water flow switch.
OPERATIONAL GUIDELINE
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PROCESS
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Effective Date: March 2016 Justin H Beal, Fire Prevention Engineer
Current Revision Date: 1/31/2025 Section 405.010
Next Revision (1) Date: 1/31/2028 Page 2 of 2
INFORMATION
As noted in the California Fire Code (CFC), the fire code official has the authority to
formulate policies they deem necessary based upon local conditions related to all
automatic fire sprinkler systems, including water flow indicating means.
The use of vane or paddle type water type flow switches in dry pipe, pre-action, and
deluge fire sprinkler systems is specifically prohibited by the currently adopted
referenced standard for fire sprinkler installations. As such, a compatible pressure
switch must be used. When a pressure switch is used on these types of fire
sprinkler systems, alarm trip valves ahead of these switches must be locked open.
Local experience with pressure switches on wet pipe, automatic fire sprinkler
systems have been found to be unreliable because of significant corrosion (hard
water) which has increased the rate of mechanical failure where these devices have
been installed.
A pressure switch may also become inoperable because inexperienced or careless
service personnel have neglected to open the small, quarter turn valve in the alarm
valve assembly.
The risk noted above has been accepted for dry, deluge, and pre-action fire sprinkler
systems as the paddle type water flow switches are not designed to accept the water
hammer effect of a quick-opening valve on a dry sprinkler system.
DEFINITIONS
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CROSS-REFERENCES
California Fire Code, Currently adopted edition