Forumites, At last I found sort of a "why not" in the May 2003 ROP. In my opinion the substantiation is poor. Interesting: the committee was not unanimous. There are other references in the May 2003 ROP, but it basicly comes down to the same. Also interesting: some committee members recognize that there will be situations where it is unavoidable to apply some form of output regulation, either be it by relief valves, pressure reducing valves or variable speed diesels. See below what it reads.
Frans Stoop TOS architecture & fire protection Netherlands <[email protected]> Tel. +31-24-324 0112 20-23-(2-2-4 and 2-2.4.1) : Accept SUBMITTER: Technical Committee on Fire Pumps, RECOMMENDATION: Revise text to read as follows: 2-2.4* The net pump shutoff (churn) pressure plus the maximum static suction pressure, adjusted for elevation, shall not exceed the pressure for which the system components are rated. 2-2.4.1 Pressure relief valves and pressure control valves shall not be used as a means to meet this requirement SUBSTANTIATION: Pressure relief valves are currently being used for this purpose in some cases. COMMITTEE MEETING ACTION:Accept NUMBER OF COMMITTEE MEMBERS ELIGIBLE TO VOTE:29 VOTE ON COMMITTEE ACTION: AFFIRMATIVE: 25 NEGATIVE: 2 ABSTENTION: 1 NOT RETURNED: 1 Vance EXPLANATION OF NEGATIVE: ISMAN: Our concern is the increase in system cost and corresponding decrease in reliability being mandated by the actions of the committee. Adequate documentation of a serious problem has been presented to the committee regarding the inability to size fire pumps for sprinkler systems with high flow and pressure demands such as ESFR systems. An inexpensive and technically sound solution was presented to the committee consistent with previous editions of NFPA 20. The committee has chosen to reject that solution without adequate substantiation and instead wants to mandate break tanks. Such a mandate will increase the cost of fire protection systems while decreasing the reliability. PUCHOVSKY: Sufficient justification has not been provided indicating why pressure relief valves cannot be used to regulate high pressures. NFPA 13 & 14 currently allow for the usp of such devices in sprinkler and standpipe systems where pressures exceed the pressure rating for which the system components have been listed. COMMENT ON AFFIRMATIVE: RESER: I have voted affirmative for this proposal but want the committee to be aware that their actions on this log will be difficult to comply with in some cases. Namely by not allowing the use of pressure control valves or pressure relief valves to control pump discharge pressure, some other means must be available. It is common to have wide fluctuations of pump inlet pressures. Consequently the designer and pump manufacturer must select a pump to supply the flow rate at the lowest inlet pressure to be expected. This has the potential for discharge over pressurization and the resulting safety and performance problems. Some other means such as variable speed drivers for fire pumps must be allowed or used. (See 20-113.) EXPLANATION OF ABSTENTION: DELERNO: There is no valid substantiation for 2-2.4.1. _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
