Data Sheet 5.11 Issue A - Research, industrial, valve ... · PDF fileRapidrop Alarm Valve model C is a double seated clapper check valve with grooved seat design which ensures positive
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Alarm Valve Model C
Rapidrop GlobalRutland Business Park, Newark Road, Peterborough, PE1 5WA, United Kingdom
FRICTIONAL LOSS 200 NB - 7.50 Mtrs.IN TERMS OF 150 NB - 7 Mtrs.EQUIVALENT LENGTH 100 NB - 6.1 Mtrs.OF PIPE ( C-120 ) 80 NB - 4.7 Mtrs.
APPROXIMATE 200 NB - 65 KgNET WEIGHT 150 NB - 42 KgWITHOUT TRIM 100 NB - 27 Kg
80 NB - 18 Kg
FINISH Red RAL 3000
APPROVAL UL Listed FM Approved
ORDERING Specify Size of valve,INFORMATION Trim details
REFERENCE NFPA 13 and NFPA 25
* For 200 NB, FM approval is rated upto 200 PSI (14 Bar)
DescriptionRapidrop Alarm Valve model C is a double seated clapper check valve with grooved seat design which ensurespositive water flow for alarm operation and is designed forinstallation in wet pipe sprinkler system. Externalbypass prevents false alarm under all supplypressure condition. In the event of variable pressurecondition, false alarm is prevented with theprovision of retard chamber, thus the design allowsfor installation under both variable and constantsupply pressure condition.
Operation of one or more automatic fire sprinklerscauses the water to flow into the sprinkler systemcausing the alarm valve to open, allowing continuousflow of water into the system and transmittal ofalarm, both electrical and mechanical.
OperationThe fire protection system initially when beingpressurized, will allow water to flow into the systemuntil the water supply and system pressure isequalized and the clapper closes the waterway. Oncethe pressure is stabilized, the fire protectionsystem is ready to be placed in service and thenthe alarm control valve must be opened. Undernormal condition, the water pressure gaugeconnected to the system side of the alarm valvewould show a higher or equal pressure reading thanthe water pressure gauge connected to the supplyside of the valve. This occurs because of the bypassline connecting downstream and upstream side ofthe alarm valve, which allows water pressure surgeto pass without lifting the valve clapper off its seat,thereby causing excessive high pressure surgeentrapped in the system side due to presence of acheck valve, which generally prevents false alarm.
Sudden high pressure surge, as might beencountered by the start-up of a large fire pumpmay lead the valve clapper to lift momentarily,allowing water to flow through grooves in the valveseat to the retard chamber. The water in the alarmline is automatically drained out, which helps toprevent false alarm due to successive transientsurge in supply pressure. Restriction assemblylocated beneath the retard chamber consists ofinlet and drain restriction orifices, which areestablished by considering the volume of the retardchamber to meet the l ist ing and approvalrequirement with regard to time-to-alarm. Theserequirements represent a balancing of the need toreduce the possible false alarm due to a transient
surge in supply pressure and to achieve desiredminimum time- to- alarm following a sprinkleroperation.
In constant pressure installation, the retardchamber is not required and the water passingthrough the groove in the alarm valve seat flowsdirectly through restriction nozzle assembly toactivate the mechanical and electrical alarm.
Installation1. Rapidrop Sprinkler alarm valve, Model-C must be
installed vertically.
2. The alarm valve must be installed in a readilyvisible and accessible location and provision tobe made in such a way that alarm line drain isvisible and accessible.
3. Where water pressure fluctuates, the variablepressure trim with retard chamber must beused. Under non-fluctuating water pressurecondition, the constant pressure trim, whichdoes not include retard chamber, may be used.
4. The valve must be installed with trim inaccordance with the trim data. Failure to followthe appropriate trim connection guidelines mayprevent the device from functioning properlyas well as void listing, approval and themanufacturer's warranty.
5. Care must be exercised while installing thecheck valve in the trim to ascertain that theyare located with the arrow mark on the checkvalve body and pointed in proper direction.
6. The contraction and expansion associated withan excessive volume of trapped air could causethe waterway clapper to cycle open and shut.This may result in false alarm or an intermittentalarm. To avoid these, it is recommended tohave breather valve in the system pipingnetwork and a vent valve at the extreme endof the system to bleed-off the air.
7. The ball valve provided on the alarm line mustbe kept open and strapped in set position.
8. Pipe connecting the retard chamber andsprinkler alarm bel l must be supportedproperly to avoid loading on the retard chamber.
9. All the newly installed system pipes must beflushed properly before alarm valve is put intoservice.
Inspection and MaintenanceA qualified and trained person must commission thesystem. After few initial successful tests anauthorised person must be trained to performinspection and testing of the system.
It is recommended to carry out physical inspection
of the system at least twice a week. The inspectionshould verify that all the control valves are in properposition as per the requirement of the system andno damage has taken place to any component.
It is recommended that the alarm valve and itsaccessories should be examined and performed forfollowing at least quarterly or as demanded by localauthorities to ensure reliable and trouble freeoperation and service.
1. Inspection and testing is to be carried out onlyby an authorized person. DO NOT TURN OFF thewater supply valve to undertake repair work orto test the valve, without placing a roving firepatrol in the area covered by the system. Thepatrol should continue until the system is backinto service. Also do inform the local securitypersonnel and alarm control station, so that afalse alarm is not signaled.
2. Open the alarm test valve. Verify that thesprinkler alarm bell and/or the pressure alarmswitch/electric alarm properly actuate. Close thealarm test valve and verify that water hasceased to flow from the alarm line drain.
3. Clean the 20 NB (3/4") strainer provided on thesprinkler alarm bell line.
4. Clean the strainer of restriction assembly.
5. Inspect the check valve clapper located on thebypass line.
False Alarm1. Inspect the valve rubber clapper face. If worn
or damaged, replace it. Be certain that dirt,stone or any other foreign object have notaccumulated under the clapper face and lodgedin the groove or holes. Clean the clapper facethoroughly. If the seat ring surface is nicked orscoured, it might be possible to repair the sameusing lapping compound. If not, replace thecomplete valve or return i t to themanufacturer's works for repair.
2. If sprinkler alarm bell is not functioning or theimpel ler is jammed, please fol low themaintenance guideline provided in the cataloguefor sprinkler alarm bell.
3. If pressure alarm switch gives a steady signal,but sprinkler alarm generates an intermittentalarm, check sprinkler alarm bell shaft. If boththe sprinkler alarm bell and pressure alarmswitch are generating intermittent alarm thencheck for the possible air which is trapped withinthe sprinkler system. Trapped air is to be bledoff. Also the intermittent alarm may occur dueto sudden pressure drop and increase in thesystem. These problems can be corrected bymaintaining a steady supply.
Caution1) The UL Listing,FM Approval and manufacturer’s
warranty are valid only when the alarm valveis installed with Rapidrop trim set and installed asper installation guidelines.
2) Pressure relief valve is required with wet pipesystem, when a rise in ambient temperaturecan cause system pressure to exceed 17.5Bar (250 PSI). A 17.7 Bar relief valve settingshould be used.
3) For proper operation of the wet system and tominimize unwanted false alarm, it is importantto remove trapped air from the system. Theair trapped in the system may also causeintermittent operation of the Water MotorAlarm during sustained flow of water.
Nominal Pressure Loss vs Flow - Alarm Valve (Model C)
NOTICE: The equipment presented in this bulletin is to be installed in accordance with the lasted publication standards of NFPA or other similar organisations also with the provision of government codes or ordinances where applicable. The information provided by us are to the best of our knowledge and belief, and are general guidelines only. Site handling and installation control is beyond our reach. Hence we give no guarantee for result and take no liability for damages, loss or penalties whatsoever, resulting from our suggestion, information, recommendation or damages due to our product. Product development is a continuous programme of Rapidrop and hence the right to modify any specification without prior notice isreserved with the company.