Pressure Relief Valves

Transcription

1 elief Valves election Process hile valves are designed to reseat after discharge, it is advisable that they are replaced, since system impurities such as piping debris, solder, and metal shavings can accumulate under the valve disc and inhibit the proper resealing of the valve. election of a relief valve should be based on the discharge capacity required for the system or vessel, based on the size of the equipment and the refrigerant being used. Minimum settings for valves should be at least 25% above the designed Maximum Operating, while additional consideration must be given inf the valve location may experience high ambient temperatures such as an equipment room or rooftop. izing valves to the maximum allowable setting will minimize the possibility of seepage or early discharge. elief valves operate automatically when the system pressure exceeds the valve set pressure and exerts a force on the valve disc that overcomes the opposing internal spring force. By code, valves may open with allowable tolerances within a +/ 3% range of stamped set pressure, with full discharge capacity realized at 10% above the actual opening pressure. elief valves conform to the American tandard afety Code for Mechanical efrigeration (AN/AA 15), and are designed and manufactured in accordance with AM ection V ivision., certifying specific capacities and identified by the AM and National Board NB stamps on each valve. These valves are also compliant with uropean Union quipment irective (P 2014/68/U), and exhibit the appropriate C marking and identification number. A elief Valve (PV) is a system safety device that has been designed to function in accordance with specific country codes to prevent and protect the operation of systems and vessels above the allowable safe levels. ischarge Capacity The minimum required discharge capacity of the pressure relief device or fusible plug for each pressure vessel is determined by the following formula, specified by the aa tandard 15, afety Code for Mechanical efrigeration: C = fl where: C = minimum required discharge capacity of the relief device, lb. air/min (kg air/sec) = outside diameter of vessel, ft (m) L = length of the vessel, ft (m) f = factor dependent on the kind of refrigerant from ischarge Capacity Chart xample of relief valve selection: nformation for vessel being protected: iameter = 1.33 ft Length= 3.33 ft = psi nformation from the table for f values: Application = 22 Value of f = 1.6 From the information provided, the required discharge capacity to protect the vessel is determined by solving the minimum discharge capacity formula: C=f L C= (1.6) (3.33) (1.33) C = 7.1 lbs of air/min Using the calculated discharge 7.1 lbs of air/min and the required pressure of psi, we can select from the product offering. Using the discharge capacity table, select the row for psi. Valves with capacities that meet the minimum discharge requirement, 7.1, are viable options. ischarge table values A K allows for selection of a valve based on the inlet and outlet sizes and configurations. f the desired valve is to have a 3/8" NPTF inlet and 3/8" Flare outlet, with the outlet being 90, valve A is acceptable since it has a discharge table rating of B.

2 elief Valves election Process Application Value of F Metric Value of F hen used on the lowside of a limited charge cascade system Application Value of F Metric Value of F hen used on the lowside of a limited charge cascade system A C A A B B A B 134a 411A 13B B C 142b 412A 143a A a 414A B A 401A 508A 401B 508B 401C 509A 402A B a 403A B A A A

3 elief Valves Certification and xplanation Certifications: Conforms to AM ection V, ivision 1 and The National Board of Boiler and Vessel nspectors, Certificate Number 16,564. Conforms to quipment irective 2014/68/U. C Certification Number 69517, B Product ervices Notified Body Number Canadian egistration Number C. Certification ocumentation Levels: Level 1 Certificate: A Certificate of Conformance can be provided based on customer request at the time of order placement, or after customer receipt of product. nformation necessary to provide a Certificate of Conformance includes: customer name, purchase order number, manufacturing part number, quantity shipped and date of shipment. Level 2 Certificate: A Certificate of Conformance an a UV 1 Form can be provided based on customer request at the time of order placement, or after customer receipt of product. nformation necessary to provide a Certificate of Conformance includes: customer name, purchase order number, manufacturing part number, quantity shipped and date of shipment. Level 3 Certificate: A Certificate of Conformance can be provided based on customer request at the time of order placement. A serialized certificate can be proviced to document the pressure setting of each valve at the point of production. xplanation: elief Valves are prefixed to designate the desired pressure setting. xamples of part numbers using prefixes for the A relief valve: To determine the applicable prefix, see chart below. For valves required at non standard pressure settings listed above, use the chart below to determine prefix by selecting the range at which your requirement falls into. with the exact pressure setting you require. A15502 A15502 A A A A etting psig psig 75 psig 240 psig 475 psig 625 psig ange ange

4 elief Valves Angle NPTF to Flare Features: Temperature ange: 40 F/ F, 40 C/149 C esigned primarily for use on liquid receiver applications above the liquid refrigerant level (it is recommended that the factory be consulted before the valves are used on other applications) atisfy AA tandard 15 code requirements for a refrigerant vessel safety device (Application information can also be found in AA uide and ata Book) Comply with AM code for unfired pressure vessels ischarge rates are certified by National Board of Boiler & Vessel nspectors esigned for maximum discharge capacities Conforms to quipment irective 2014/68/U, CN, Compatible with all CFC, CFC and FC refrigerants and oils NPTF Flare Outlet B C (in) C (mm) (in) (mm) t t ischarge (lb) (kg) A /8 3/ B psi A /8 1/ B psi B /4 3/ B psi B /4 1/ B psi A /2 5/ C psi A /8 1/ C psi ischarge Capacity (lb air/min) BA ischarge Capacity (kg air/min) tandard etting e Non tandard etting es: ange ange 8/23/2017

5 Features: elief Valves Atmospheric NPTF nlet Temperature ange: 40 F/ F, 40 C/149 C esigned primarily for use on liquid receiver applications above the liquid refrigerant level (it is recommended that the factory be consulted before the valves are used on other applications) atisfy AA tandard 15 code requirements for a refrigerant vessel safety device (Application information can also be found in AA uide and ata Book) Comply with AM code for unfired pressure vessels ischarge rates are certified by National Board of Boiler & Vessel nspectors esigned for maximum discharge capacities Conforms to quipment irective 2014/68/U, CN, Compatible with all CFC, CFC and FC refrigerants and oils NPTF nlet B (in) B (mm) C (in) C (mm) t (lb) t (kg) ischarge A / A A / A A / B psi B / B psi ischarge Capacity (lb air/min) BA ischarge Capacity (kg air/min) tandard etting es: Non tandard etting es: ange ange 8/23/2017

6 Features: Temperature ange: 40 F/ F, 40 C/149 C elief Valves nternal esigned primarily for use on liquid receiver applications above the liquid refrigerant level (it is recommended that the factory be consulted before the valves are used on other applications) atisfy AA tandard 15 code requirements for a refrigerant vessel safety device (Application information can also be found in AA uide and ata Book) Comply with AM code for unfired pressure vessels ischarge rates are certified by National Board of Boiler & Vessel nspectors esigned for maximum discharge capacities Conforms to quipment irective 2014/68/U, CN, Compatible with all CFC, CFC and FC refrigerants and oils NPTF B (in) B (mm) C (in) C (mm) t (lb) t (kg) ischarge B 34 3/ B psi A A / F ischarge Capacity (lb air/min) BA ischarge Capacity (kg air/min) tandard etting es: Non tandard etting es: ange ange 8/23/2017

7 elief Valves traight Thru Features: Temperature ange: 40 F/ F, 40 C/149 C esigned primarily for use on liquid receiver applications above the liquid refrigerant level (it is recommended that the factory be consulted before the valves are used on other applications) atisfy AA tandard 15 code requirements for a refrigerant vessel safety device (Application information can also be found in AA uide and ata Book) Comply with AM code for unfired pressure vessels ischarge rates are certified by National Board of Boiler & Vessel nspectors esigned for maximum discharge capacities Conforms to quipment irective 2014/68/U, CN, Compatible with all CFC, CFC and FC refrigerants and oils NPTF nlet to Flare Outlet * NPTF Flare B (in) C (in) C (mm) t (lb) t (kg) ischarge A /4 3/ A A /8 3/ B psi A /8 1/ B psi B /4 3/ B psi B /4 1/ B psi A /2 5/ C psi A /8 5/ C psi A /8 1/ C psi ischarge Capacity (lb air/min) BA ischarge Capacity (kg air/min) tandard etting es: Non tandard etting es: ange ange 8/23/2017

8 elief Valves traight Thru NPTF nlet to NPTF Outlet * PTF eat NPTF NPTF B (in) C (in) C (mm) t (lb) t (kg) ischarge A /8 3/ C psi A /2 3/ C psi A /4 3/ A A / A /4 1 1/ F A F A /2 1/ A /2 3/ A /4 3/ A18422 * 3/4 3/ psi A * psi A 18 * 1 1/4 1 1/ K A * 1 1 1/ K traight Thread nlet to Flare Outlet nlet Outlet B (in) C (in) C (mm) t (lb) t (kg) ischarge B /8 14 UNF 2A 5/ C psi traight Thread nlet to NPTF Outlet nlet Outlet B (in) C (in) C (mm) t (lb) t (kg) ischarge B /8 14UNF 2A 3/ B /16 12UNF B /8 12UNF 2A 1 1/ F A /8 14UNF 2A 3/ tandard etting es: Non tandard etting es: ange ange