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  • A photograph of a G3902LF in a surface-mounted cabinet.
  • A photograph of a G3907LF in a recess-mounted cabinet.
  • A photograph of a G3900 valve without the cabinet (for reference).

Guardian G3902LF and G3907LF Tempering Valves, 81 Gallon Capacity w/ Mounted Stainless Steel Cabinet

Item #: G3902LF
Discontinued; see below

Normal Availability: Discontinued; see below

Product Description

APPLICATION NOTEThese products were discontinued in September, 2021.  Repair parts are no longer available. The Guardian G604X series of valve cabinets are a lower maintenance and more affordable successor to the G3900LF series.

The G9802LF is a G3900LF tempering valve contained within a surface-mounted steel cabinet.  The G3907LF is a recess-mounted cabinet (select the "recess mount" checkbox above to select). This unit is suitable for use with a single installation of emergency showers and safety stations, and with multiple installations of emergency shower, eyewash, eye/face wash, dual purpose eyewash/drench hose, drench hose and safety station units.

We carry a full line of tempering valves ranging in capacities from 6 to 81 gallons per minute (GPM). The valve must be properly matched to the flow capacity of the safety station in order to deliver water within the tepid range.  

Application: Tempering valve to blend hot and cold water to deliver tepid water. Valve has flow capacity of 3.0 to 81 gallons per minute (GPM). Valve can be used with a single installation of emergency showers and safety stations, and with multiple installations of emergency shower, eyewash, eye/face wash, dual purpose eyewash/drench hose, drench hose and safety station units.

Temperature Control: Valve has bimetallic thermostat that senses incoming water temperature and automatically blends water to 85 °F (29 °C). High temperature limit stop is set to 90 °F (32 °C). Valve has dial thermometer on outlet to monitor temperature of delivered water. Note: Valve may need to be adjusted when installed based on incoming water temperature. Refer to “Installation Instructions” for further information.

Fail Safe: In event of restriction or failure of hot water supply, internal bypass allows valve to deliver cold water to emergency unit. In bypass mode, valve will deliver 40 GPM of cold water at 30 PSI flow pressure. In event of loss of cold water supply, valve will close and not deliver water.

Flow Capacity: Refer to chart below for flow capacity of valve at specified pressure drops:

System Pressure Drop (psi) 5 10 15 20 25 30 35 40
Flow rate (gallons per minute) 53 64 72 81 90 99 108 117
System Pressure Drop (bar) 0.3 0.7 1.0 1.4 1.7 2.1 2.4 2.8
Flow rate (liters per minute) 201 242 273 307 341 374 409 443

Supply Temperature: Minimum hot water supply temperature is 140 °F (60 °C).

Supply Pressure: 30 PSI minimum supply pressure is required for proper operation of valve. Maximum supply pressure is 125 PSI. Maximum hot to cold water pressure differential is 5%.

Mounting: Tempering valve is mounted in either a surface mounted cabinet (G3902LF) or recess-mounted model with a 3/8” return (G3907LF). Both cabinets have a hinged door with lock and are constructed from 16 gauge Type 304 stainless steel.

Inlets: 1-1/4" NPT female hot and cold water inlets. Inlets can be rotated 360 degrees for top or bottom supply. Each inlet has integral water strainer, check valve and supply stop.

Outlet: 1-1/2" NPT female outlet.

Quality Assurance: Valve is completely assembled and water tested prior to shipment. Valve is certified to ASSE 1071. Valve is certified to meet low lead requirements of wetted surface area less than 0.25% lead by weight.

Application Note: Pursuant to ANSI Z358.1-2014, the water delivered by emergency equipment should be "tepid". Tepid is defined as moderately warm or lukewarm, and is generally considered to be between 60 °F (15 °C) and 90 °F (32 °C). However, in certain circumstances, a chemical reaction may be accelerated or otherwise affected by the water temperature. Please consult with a medical advisor to determine the optimum delivered water temperature prior to specifying, installing or using a tempering valve.

Tempering valves will not deliver the appropriate water temperature if the system has not been sized correctly. Please refer to the flow capacities and supply pressure requirements listed above when designing the tempered water system and selecting tempering valves.

Tempering valves, like all emergency eyewash and shower equipment, must be installed in accordance with the manufacturer’s instructions and maintained on a regular basis. Under ANSI Z358.1-2014, all emergency equipment should be activated weekly and inspected at least annually. Tempering valves should be treated the same and, in addition, must be regularly cleaned and cycled.


Documentation available:  G3902LF and G3907LF specification sheets w/ measured drawings, installation, operation and maintenance guide, and written specifications (Word format).

Dimensions - The stainless steel enclosure measures 16" h x 16" w x 8" d (41 x 41 x 20 cm).

Warranty Information

2-year manufacturer limited warranty.

Other Details

Manufactured in: USA

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