Wet Alarm Check Valve
Technical Data
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Standard trim
Retard chamber
Water motor alarm
Pressure switch
Approvals
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Product Description
Lifeco Wet Alarm Valves are designed to hold back water pressure in the piping system until the sprinkler is activated, to be used in wet pipe sprinkler installations in buildings not subject to freezing temperatures. Alarm valve includes trim packages valves, gauges, pressure switch, fittings and nipples to provide retard chamber connection,drain connections and alarm test bypass.
Retard Chamber
This is a valve accessory which may be used for variable pressure wet systems where mechanical motor alarms or pressure switches are used. In situations where excessive water pressure surgers occur the retarding chamber is needed to collect excess water from the alarm valve and feed water back into the main drain, before activating the alarm.
Water Motor Alarm
This is a hydraulically driven mechanical gong that automatically sounds a continuous alarm when the sprinkler system activates.
Installation & Maintenance
General ::
Lifeco Alarm Check valve is a wet pipe sprinkler system water check valve, which is installed in the wet pipe sprinkler system. It is designed so that water pressure in the piping system will hold back water pressure at the valve until such time as a sprinkler is activated, hence activating the alarm.
Alarm check valve can generate alarm in two ways:
Mechanically - by means of a water motor gong and/or
Electrically - by means of alarm pressure switch, which is electrically connected to any alarming device.
The retard chamber is used along with alarm check valve in Automatic Sprinkler system. The retard chamber is a valve accessory, which may be used for variable pressure wet sprinkler system, where mechanical water motor alarm and/or alarm pressure switches are used.
Water motor alarm (gong) is used along with alarm check valve in Automatic Sprinkler System. The water motor alarm is hydraulically driven that automatically sounds a continuous alarm when sprinkler system actuates. It is easily mounted on an outside building wall. Water motor alarm can generate sufficient sound that can be heard by human being.
Usually the wall thickness on which water motor alarm is mounted ranges from 2 to 13. The water motor and gong bell is made of corrosion resistance aluminium alloy and stainless steel. The gong bell is painted red.
Operation/Installation Lifeco alarm check valve has flange- by-flange connecting ends with a set of auxiliary piping called trim set.
To put the system in service the water is allowed to flow into the system until the pressure gauge on the system side of the alarm check valve should indicate water pressure equal to or greater than the water pressure indicated on the gauge located on the supply side. This causes the clapper of the alarm check valve to close tightly on the seat ring.
In the variable pressure condition, in most of the cases pressure on the system side will be found greater than the water supply pressure. This condition is achieved because pressure surges and fluctuations in the water supply is allowed to pass through the external by pass trim to minimise the false alarms.
In some cases temporary pressure surges or fluctuations are large enough to move the valve clapper, are allowed to enter into the retard chamber, where the water can accumulate and get drained through the restricted drain without causing any false alarm.
When a sprinkler operates, the sustained water flow through the sprinkler relieves the system pressure. The greater supply pressure then causes the clapper valve to open, allowing unobstructed supply of water into the system. Simultaneously water flows through the seat ring opening and via trim lines into the retard chamber. But now the retarding chamber will fill faster than water can drain through the restricted drain of the alarm trim. The water fills the chamber and then flows into the water motor alarm and or actuate the alarm pressure switch.
Retard chamber should be installed properly between the alarm check valve and the water motor alarm and/or an electric alarm pressure switch.
The water motor alarm must be properly installed as per the requirements of NFPA standards and any other authority having jurisdiction. In order to ensure the normal operation the total length of 3/4 supply wet pipe line from the alarm valve, dry pipe valve or deluge valve to the water motor alarm should not exceed 75 feet, and the number of fittings should be kept to a minimum.
Where the length exceeds 75 feet, the diameter of the supply piping should be increased to 1 or 1-1/4 to reduce friction losses. The water motor alarm should not be located more than 20 feet above the alarm check valve, dry pipe valve or deluge valve to which it is connected.
To ensure clean water supply to the water motor alarm, a 3/4 screen filter (Strainer) must be installed in the supply line.
Caution :
Care must be taken to avoid air trapping inside the system. The pressure surge can compress this trapped air and allow the clapper to move off the seat ring, thus causing the false alarm. Therefore while putting the system in service it is recommended to bleed off the confined air and to fill the system with water to the fullest extent possible.
Constant Pressure Condition :
Under constant pressure conditions the system and the supply pressure will be same. When there is no considerable surge and fluctuation in pressure retard chamber is not necessary. When a sprinkler operates the system pressure drops allowing the alarm clapper valve to open. When the water flows into the system simultaneously it flows into the alarm line thereby operating the alarming devices.
Maintenance :
It is imperative that the alarm check valve and its related equipment must be inspected and tested on regular basis to ensure proper and trouble free operation of the system. Several areas to be routinely inspected are:
Clapper Facing :
The clapper facing should be checked for wear and tear and to ensure that it is free from dirt and foreign matter. Replace the facing if it is damaged. Clean the facing if it is found dirty.
Seat Ring :
The seat ring should be visually checked for nicks and for stones, dirt or other foreign matters lodged in the groove or holes. Clean the seat ring thoroughly.
By-pass Check Valve :
The check valve in the external by-pass trim set should be checked for obstructions, and must be cleaned properly.
Retard Chamber :
The outlet plug and drain plug assemblies should be checked properly for the obstructions and must be cleaned thoroughly.
Alarm Test Valve, Main Drain Valve and Inspectors Test Valve
Ensure that all controlling valves are in their set position and are not leaking.
The next step
For more information about Wet Alarm Check Valve, either email the sales team or call +44 (0) 870 066 4401.
