Construction Standpipes and PRVs – A Question of Pressure

Standpipe systems are required for buildings under construction where a standpipe will be required in the finished condition – i.e., where the building is greater than 30 feet above the lowest level of fire department vehicle access. Such construction standpipes are required prior to construction reaching 40 feet above the lowest level of fire department vehicle access. In Massachusetts, this is required both by the 780 CMR Massachusetts State Building Code (Section 3311) and by 527 CMR 1.00 Massachusetts Comprehensive Fire Safety Code (Section 16.3.5).

Construction standpipes are usually dry, manual standpipes – i.e., the fire department will provide the required flow and pressure for the standpipe via a fire engine connected to the municipal water supply pumping into a fire department connection. However, the construction standpipe itself is not generally connected directly to the municipal water supply. Temporary fire department connections are often used for this purpose, as it allows the piping installation for the permanent system to take place with minimal impairments to the construction standpipe.

At least one construction standpipe is required to be provided. From a construction efficiency standpoint, builders will often use a final-condition standpipe as the construction standpipe, extending the standpipe as the building increases in height. Provided the standpipe is not in conflict with other construction, this is usually far simpler than providing a separate, dedicated standpipe that will be removed when construction has concluded. Construction standpipes should have a sign indicating the required pumping pressure at the inlet location. Some may even give a required pressure for each floor or bank of floors within the building. Barring a sign indicating otherwise, the fire department will typically pump into a fire department connection at 150 psi.

NFPA 14 Installation of Standpipe and Hose Systems requires Class 1 standpipes to limit pressure at each fire department hose valve to less than 175 psi under both flow and no flow (i.e. static) conditions. In buildings with fire pumps, pressure reducing valves (PRVs) are often provided at the standpipe hose valves to limit this pressure where the fire pump output is capable of exceeding 175 psi at the hose valve location. Some systems may have PRVs only on lower floors where the pressure may exceed 175 psi with standard hose valves on upper levels; while other systems may have PRVs at each hose valve in the building.

PRVs limit the pressure leaving the valve and entering the fire hose. They generally have a spring-operated mechanism that varies the opening inside the valve; with some valves being field-adjustable and others being set at the factory prior to installation. If PRVs have been installed in the construction standpipe, the valves’ settings are of critical importance to firefighters.

When final-condition PRVs are installed in a construction standpipe without proper coordination and planning, unseen water supply problems may await firefighters using the standpipe.  These issues can be result where standard hose valves were initially installed in the construction standpipe but are being changed to final-condition PRVs as the construction progresses; and/or, similar issues can arise where field-adjustable PRVs are installed but not yet adjusted to the correct operating pressure. A potential oversight in this process is that the updated pressure required based on the inclusion of new PRVs is not reflected in the fire department connection signage. What’s more, depending on the system demands and configuration, the water pressure and volume requirements may not even be achievable by the fire department via a fire engine with PRVs installed at the hose valves. Inadequate pressure and volume will render the standpipes ineffective during a fire incident, which places undue risk on responding firefighters and hampers their ability to fight the fire.

There are several options available to ensure that the proper water flow and pressure will be available at the hose valves, including:

  • Configuring the construction standpipe such that only traditional hose valves are required and utilized
  • Field adjustable PRVs should be verified being as “wide open” to the greatest extent that the manufacturer’s instructions will allow; and, it should be verified by the Registered Design Professional (RDP) what pressure is required at the fire department connection for the construction standpipe based on the inclusion of the PRVs
  • Factory-set PRVs should be verified as being set for the correct pressure at each floor per the RDP and Construction Documents; and, it should be verified by the RDP what pressure is required at the fire department connection for the construction standpipe based on the inclusion of the PRVs
  • In all cases, fire department connection signage should accurately reflect the current pressure requirements for the system and updated, if needed, based on the replacement of standard hose valves with PRV hose valves as construction progresses

Regardless of what options are utilized, a key component is regular communication and planning with the local fire department during the construction process. Including the fire department in the process and keeping them up to date with how to interact with the building and construction site is critical to meeting their expectations and enabling the standpipes to be fully functional during a fire emergency.

If you have questions on construction standpipes, impairment planning, or construction fire safety, please contact our office.