Protection for Safety Showers
Type FP valves installed on emergency shower and eyewash station. One FP senses impending freeze-up and opens to allow bleed flow to protect piping and equipment. The other FP valve senses elevated water temperature and bleeds the system to prevent the possibility of scalding water. As cooler supply water refills the system, the valve automatically closes. Both valves must be located to assure flow through the entire system. Avoid any dead legs.
can also be automatically protected against excessively
high temperatures with Ogontz self-actuated control
valves. A reverse-acting Type FPR
valve is used to protect personnel from scalding
water. Two typical scald applications are emergency
safety showers and eyewash stations.
In scald protection systems, overheating of water lines can be caused by three conditions:
1. Solar radiation -- Exposed outdoor lines are especially susceptible to high heat absorption from the sun in the southern states and in equatorial areas. At times, this can also be a problem in temperate areas. Water used in outdoor safety showers in these areas can easily exceed 150°F, presenting potential burn problems, unless some type of scald protection is employed.
2. Auxiliary Heating -- Many exposed water lines require auxiliary heating by means of steam or electric tracing because of the danger of freezing. Since these hot lines are often run to safety showers and eyewash stations and are not temperature-controlled, they present scald dangers to personnel. Ogontz can provide both freeze and scald protection to these lines.
3. Storage Tanks --In some plants, heated water storage tanks are incorporated in the water supply system to provide heated water for emergency purposes, such as safety showers or eyewash stations. If the water is overheated because of some heating control malfunction, scalding of personnel is possible. Therefore, scald protection and possible freeze protection should be provided.
In any of the three situations outlined here, the solution is to bleed the hot water quickly from the system, and keep the line full of water that's not dangerous. It should not be hot enough (above 100°F) to scald, or cold enough (below 35°F) to freeze.
Two types of F valves can be used for scald protection on safety showers and eyewash stations. Both types open on temperature rise. The Type F is an angle-type block valve that mounts off a tee on the main water line. The FP is an inline-type valve that is installed directly in the main line.
Scald Protection System Design
An important design consideration is that the valve be installed where it will be subjected to the same conditions as the rest of the system. The location of the valve must be representative of the entire water system. For example, if the water line is exposed to solar radiation, the scald protection valve should not be located in a shaded or partially shaded area.
F and FP
The following fundamental installation procedures should be employed for all scald protection valves.
1. Flush out the entire system to clean out dirt and foreign particles.
2. Valve location is extremely important. Minimize dead legs to prevent pockets of overheated water. If both scald and freeze protection valves are employed, locate the freeze valve downstream of the scald valve.
3. Do not insulate either the freeze or scald protection valves.
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