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AMERICAN NATIONAL STANDARD K61.1-1951 2.9.4 Pressure relief valves shall be so ar- remaining openings, the restricted opening or ranged that the possibility of tampering will be openings or those having the lowest flow shall be minimized.If the pressure setting adjustment is used to establish the flow rate marked on the external,the relief valves shall be provided with manifold nameplate. The marking shall be means for sealing the adjustment. similar to that required in 2.9.7 for individual 2.9.5 Shut-off valves shall not be installed valves. between the pressure relief valves and the con- 2.9.10 A hydrostatic relief valve or equivalent tainers or systems described in Sections 3, 6, 7 shall be installed in each section of piping and 8, except that as shut-off valve may used (including hose)in which liquid ammonia can be where the arrangement of this valve is such as isolated between shut-off valves so as to relieve always to afford required capacity flow through the pressure which could develop from the the relief valves. trapped liquid. If an equivalent pressure reliev- NOTE: The above exception is made to cover such cases as a ing device is used, the maximum accumulative threeway valve installed under two pressure relief valves, pressure possible within the.system shall not each of which has the required.rate of discharge and is so exceed the limits of the system. ' installed as to allow either of the pressure relief valves to be closed off.butdoes not allow both pressure relief valves to be 2.9.11 Discharge from pressure relief valves closed off at the same time.Another exception to this may be shall not terminate in or beneath any building. where two separate pressure relief valves are installed with individual shut-off valves.In this case,the two shutoff valve stems shall be mechanically interconnected in a manner 2.10 Safety which will allow full required flow of one pressure relief valve at all times.Still another exception is a pressure relief valve See CGA Pamphlet G-2 and TF1 Operational manifold which allowsone valve of two,three,fouror more to Safety Manual M-2 (See Appendix C for be closed off and the remaining valve or valves will provide availability). not less than the rate of discharge shown on the manifold aVay). nameplate. 2.10.1 Personnel required to handle ammonia shall be trained in safe operating practices and 2.9.6 Pressure relief valves shall have direct the proper action to take to emergencies. AW communication with the vapor space of the 2,10.2 If a leak occurs in a permanent storage +�1 container. installation, the personnel trained for and 2.9.7 Each pressure relief valve used with designated to act in such emergencies shall: systems described in Sections 3,4,6,7 and 8 shall (a) See that persons not required to deal with be plainly and permanently marked as follows: an emergency are evacuated from the contami- (a) With the letters"AA"or the symbol"NH;', nated area. (b) The pressure in pounds per square inch (b) Put on suitable respiratory protection. gage (psig) at which the valve is set to start-to- (c) Wear gauntlet type plastic or rubber gloves, discharge. plastic or rubber suits and protective boots in (c) The rate of discharge of the valve in cubic heavily contaminated areas. feet per minute of air at 60 F (15.6 C) and (d) Shut-off the appropriate valves. atmospheric pressure. (e) Notify state or federal governmental regu- (d) The manufacturer's name and catalog latory authorities as may be appropriate. number. 2.10.3 All permanent storage installations For example, a pressure relief valve marked shall have on hand,as a minimum,the followin AA-250-4200 (air)would mean that this valve is g suitable for use on an anhydrous ammonia equipment for emergency and rescue purposes: container; that it is set to start-to-discharge at '(a) One full face gas mask with one industrial 250 psig(1720 kPa);and that its rate of discharge size ammonia canister and at least one spare (see Sections 2.9.1, 2.9.2, and 2.9.3) is 4200 ammonia canister in a readily accessible location. cubic feet(118.9 ms) per minute of air. Positive pressure self-contained breathing appa- ratus must be used in ammonia contaminated 2.9.8 The flow capacity of the pressure relief atmospheres that are immediately dangerous to valve shall not be restricted by any connection to life or health. Gas masks and self contained it on either the upstream or downstream side. breathing apparatus must be approved by 2.9.9 The manufacturer or suppplier of apres- NIOSH/MSHAunder provisions of 30 CFR Part sure relief valve manifold shall Publish complete II. data showing the flow rating through the com- !An ammonia gas mask willprovide effective respiratory bined assembly of the manifold with pressure protection in concentrations of ammonia in air that are not relief valves installed.The manifold flow rating immediately dangerous to lifeor health(2500 ppm or less)for short periods of time. A gas mask is not recommended for f shall be determined by testing the manifold with respiratory protection in concentrations exceeding this all but one valve discharging. If one or more amount Faceaiece fitting shalt be used to determine the openings have restrictions not present in the ability of each individual gas mask wearer to obtain a 13