My understanding is PIVs are needed based on NFPA 13 22.214.171.124.1.2 - at least one indicating valve is required in each source of supply. If for some reason you can't put a control valve on your supply line inside the building, you can use a PIV instead.
One place I saw PIVs used was outside an existing building. My assumption at the time was that they had more than one connection to the water main, and this would allow for each supply to be isolated.
I've also seen them used for convenience. For example, when it would be beneficial to have system control in an area that is subject to freezing.
What is the purpose of having a PIV at 40 ft (12 m) ? If you unferstand the « why » behind, you will better understand the purpose.
The aim is to be able to isolate your sprinkler system from the water supply in case of total loss of your building. There are many possible reasons such as a change in occupancy, an impaired system...
If your sprinklers cannot control the fire, there might be a moment when you need to shut the supply to the system to save water for other systems and manual firefighting.
If the building collapse, you also need to isolate the system.
Here comes the 40 ft distance. Most industrial buildings are 30 ft high max. in case of collapse of the wall, the PIV is still accessible.
This means also that the distance may be reduced for a lower building (or increased).
Therefore, for reliability purposes, order of preference is
1. Piv ar safe distance
2. Piv wall (valve on the outside side of the bldg)
3. Valve inside
Some insurance companies such as FM Global (Factory Mutual) strongly recommend PIV and accept other situations on a case by case study (if putting the PIV valve at 40 ft means having the valve in the middle of the road, it doesn’t really make sense).
My motto : every time there is a rule, try to understand the reason behind. It will also help you to accept (or not) alternative solutions.
It has to be outside of the Collapsible zone of the building which 40'
It would be good if ANY Civil Engineering types could chime in in this one. ZS, do you mean a PIV as the only means? I am assuming you mean in addition to other indicating control valve(s) inside. In which case, correct me if I’m wrong, but as far as a PIV requirement, I think NFPA 24 used to require a yard PIV (unless the AHJ said otherwise) up through the 2007 edition. But that section (Chapter 6) has since changed. (I think it now only says what to do IF you have one.) With most AHJ,’s their municipal codes are available and searchable on-line, that is where I look for requirements on a case-by-case basis. Around here, some require PIV’s, others do not, and some require it if there is no outside access to the riser room. In some situations wall P.I. is an option, but as Franck says, building collapse zones sometimes factor in. I also check the public works/water purveyor standard details. And my notes from previous jobs. But when in doubt, for me it often comes down to a phone call or email to the AHJ, then document that communication. Similar applies to FDC location requirements.
126.96.36.199.1.1 Each sprinkler system shall be provided with a listed indicating valve in an accessible location, so located as to control all automatic sources of water supply.
A.188.8.131.52.1 A water supply connection should not extend into a building or through a building wall unless such connection is under the control of an outside listed indicating valve or an inside listed indicating valve located near the outside wall of the building. All valves controlling water supplies for sprinkler systems or portions thereof, including floor control valves, should be accessible to authorized persons during emergencies.
Outside control valves are suggested in the following order of preference:
(1) Listed indicating valves at each connection into the building at least 40 ft (12 m) from buildings if space permits
(2) Control valves installed in a cutoff stair tower or valve room accessible from outside
(3) Valves located in risers with indicating posts arranged for outside operation
(4) Key-operated valves in each connection into the building
the reasoning behind (1) is to avoid collapse of a wall, the reasoning behind (2) and (3) is to be able to isolate a system without entry.
The local AHJ may not allow a wall mounted PIV for the same reasons.
In every case, the reasoning is to be able to isolate a system for maintenance, or repair.
One very important reason was left out in this thread. Codes like these were adopted,usually because of an incident that occurred and there was loss of life, property or severe injuries.
PIV’s let firefighters know that the water supply serving the fire sprinkler systems and or FDC connections has water to fight the fire before they send a crew in the building to battle the fire. Without PIV’s in good working conditions there is no way of knowing those valves have been tampered with or shut off by a maintenance crews to fix a water supply line
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