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  • A photograph of a Guardian G3850LF Tempering Valve, 44 Gallon Capacity, Redundant Bypass.

Guardian G3850LF Tempering Valve, 44 Gallon Capacity, Redundant Bypass

Item #: G3850LF
Discontinued; see below

Normal Availability: Discontinued; see below

Product Description

APPLICATION NOTEThis product was discontinued in September, 2021.  Repair parts are no longer available. The Guardian G6040 is a higher capacity, lower maintenance, and more affordable tempering valve that is designed as a successor to the G3850LF.

The G3850LF is a G3800LF valve equipped with an external bypass for “second stage” mixing of water, providing both internal and external fail-safe mechanisms. 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. The G3800LF valve is available in two additional configurations. The G3802LF is the same valve but installed in a surface-mounted stainless steel cabinet. The G3807LF is installed in a recess-mounted stainless steel cabinet.

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 is supplied with external bypass for “second stage” mixing of water. Valve has flow capacity of 3.0 to 44 gallons per minute (GPM). Valve can be used with 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.

Internal Fail Safe: In the event of restriction or failure of the hot water supply, the internal bypass allows valve to deliver cold water to emergency unit. In bypass mode, valve will deliver 20 GPM of cold water at 30 PSI flow pressure. In event of loss of cold water supply, valve will close and not deliver water.

External Fail Safe: In addition to primary blending, unit is furnished with external thermostat to sense temperature of outlet tempered water. If temperature of tempered water rises above 90 °F (32 °C), additional cold water is added to tempered water to lower water temperature to 90 °F (32 °C).

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) 20 25 30 33 35 38 43 50
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) 76 95 114 125 132 144 163 189

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: Furnished with heavy duty mounting bracket for securing valve to panel or wall.

Inlets: 1-1/4" NPT female hot and cold water top inlets. Each inlet has integral water strainer, check valve and supply stop.

Outlet: 1-1/4" 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:  G3850LF specification sheet w/ measured drawings, installation, operation and maintenance guide, and written specifications (Word format).

Common replacement parts: RK3800A rebuild kit and RK3800B checkstop kit.

Shipping weight - 40 lb (18.1 kg).

Warranty Information

2-year manufacturer limited warranty.

Other Details

Manufactured in: USA

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