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Dry Pipe Sprinkler Systems — Ensuring Proper Maintenance

Updated: May 2



Key Steps for Ensuring Proper Maintenance of a Dry Pipe Sprinkler System

In areas that are subject to temperatures below 40 deg F, you will find a dry pipe sprinklers system. This sprinkler system has a dry pipe valve that holds back water from the supply source. The valve is held in the closed position by air pressure in the system piping. When a sprinkler head opens, the air pressure drops, and the valve opens allowing water to fill the system and flow from the open sprinkler. This system requires maintenance to ensure reliable operation.

 

Piping

Since the piping is subject to freezing, it must be installed to allow complete draining of the system. This involves proper sloping of the pipe back to the riser and the use of remote auxiliary drains. The proper drainage of the system is a critical installation and maintenance consideration. Small areas with trapped water will freeze and cause the pipe to burst and cause water damage. Ice plugs that do not burst the pipe will prevent water from traveling through the system and impair protection. The inspection process should verify proper drainage and slope of the pipe to drain.

 

Maintenance and verification of proper pipe draining is key to preventing water damage claims. Use of drum drip assemblies on drains requires routine inspection and maintenance during freezing weather. Failure to perform these maintenance tasks will result in a frozen system and water damage.

 

Dry Pipe Valve

The dry pipe valve holds back water until a sprinkler opens and lowers air pressure and allows the valve to open. This is a mechanical device that must be able to operate quickly and reliably. It needs routine testing to ensure the internal components operate promptly. Testing standards call for an annual trip test. Two years of these tests can be done with no full flow into the piping system. Every third year the piping system must be filled to allow the timing of water to the remote test point.

 

The testing also allows internal maintenance of the valve seats that are at the air/ water control point. Routine cleaning of these valve seats will provide more reliable sealing of the valve and operation of the valve.

 

Data gathered during the testing will include air pressure at start of test, air pressure at valve trip point, time to trip and time to discharge water at the test point. All of these are important test points and can be tracked over time to give an indication of interior pipe condition. If the time for water to travel is increasing, then the interior of the pipe is getting more corroded. This can lead to the need for a system flush to restore proper flow. Slow trip times for the valve may indicate valve maintenance is needed to assure proper operation.

 

Dry Valve Enclosure

The dry pipe valve must be kept at over 40 deg. F at all times. This requires an insulated and heated valve house. The maintenance should include inspection and maintenance of the heating system. A best practice is to have a low temperature alarm in the valve enclosure to alert you to heat loss. A frozen dry pipe valve will cause severe water damage.

 

Air Supply

The dry pipe system must have an adequate size air compressor or other supply of air to hold back the dry valve. The amount of air pressure is based on the valve specifications and normal supply pressure. Routine maintenance of the air supply involves verifying that the air pressures are proper. Mechanically the compressor must function and deliver the correct volume of air to allow reset of the valve. If there are automatic air supply systems, the electrical and sensors involved must be maintained and tested.

 

Some systems use nitrogen as the system gas to prevent internal corrosion.

If using air pressure, consider that the air entering the system will contain water vapor relative to humidity. A drier may be needed to prevent water from being added to the system via compressed air. Failure to properly maintain the drier can result in ice plugs in dry pipe systems that can impair protection.

 

Obstruction Investigation

As the internal pipe surfaces are alternately wet and dry from testing, there is inherent corrosion inside dry pipe sprinkler system. Pipe scale can accumulate and cause slower transit time for water or cause test outlets to plug. There is a requirement for five-year testing for obstructions. There are procedures to follow when systems show signs of obstructions.

 

Dry Sprinklers

While not part of a dry pipe system, these sprinklers are used to protect areas subject to freezing when the balance of the building is protected with a wet pipe sprinkler system. Since these sprinklers are subject to freezing at the operating end and building heat at the supply end, they can fail and cause water damage. These sprinklers are on an accelerated testing schedule needing to be tested or replaced every ten years after being in service for fifteen years.

 

Why focus on dry pipe system maintenance?

The dry pipe sprinkler system introduces a number of extra components to the sprinkler system. The dry valve has internal moving parts that can fail. The system itself can corrode and slow water travel and reduce flows needed for proper discharge. Piping systems that freeze can cause damage. Air supplies that are not maintained can allow systems to trip or high moisture in the air supply will cause excess corrosion and ice plugs.

 

All of these conditions are unique to a dry pipe sprinkler system and need careful attention to assure reliable operation. Lack of maintenance and testing is a common source of risk control recommendations, removal of sprinkler credits and the source of water damage claims. If your inspection and maintenance providers cannot detail how they have looked at these items, question the thoroughness of their work.

 

The Driehaus Difference

We know how insurance companies approach maintenance of sprinkler systems and dry pipe systems specifically. We can offer you assistance in arranging proper testing and maintenance to provide the best of system reliability and property protection. Call us at 513-977-6860 or reach out to us using the contact tools on our website, www.driehausins.com. We want to be your insurance agent and welcome your questions and calls.

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