The INVALCO Series 504 back pressure valve holds back pressure on vent lines from separators, treaters, dehydrators, compressor stations and gas gathering systems. Line pressure reaches the diaphragm through the hollow stem (internal sensing line), which reduces the chance of a blocked external sensing line. When line pressure exceeds the spring setting the valve opens and relieves through the orifice; as pressure drops the spring reseats the plug. Ductile body, RNCE adaptable for sour service; parts interchange with the Series 503 cast iron RDSG-201 and RDSG-301.
Key specifications
Body: Ductile A-395
End connections: 2" FNPT
Diaphragm: Steel case, 26 sq. in., nylon-reinforced Buna-N diaphragm
Containment pressure: 125 psi (all models); this is the maximum working pressure, and above the maximum spring setting the valve is fully open and uncontrolled
Temperature: -20 to 250 °F
Trim: 416 stainless with molded fluoroelastomer plug, 1-3/4" orifice
Flow capacity (fully open): Cv 28.5, Cg 970
Pressure increase, closed to full open: 0-25 psi spring: 2.7 psi; 20-40: 4.0 psi; 40-60: 9.5 psi; 60-125 (60-100 in ordering table): 10.5 psi
Setting: Factory set at the midpoint of the selected range; select the spring to suit the working range for best sensitivity
Approx. size / weight: 23.5" tall x 9" case; 45 lb
How to specify / order
2" RSDG-201-504, spring 0-25 psi: part number 80006279
2" RSDG-201-504, spring 20-40 psi: part number 80006280
2" RSDG-201-504, spring 40-60 psi: part number 80006281
2" RSDG-201-504, spring 60-100 psi: part number 80006282
State the desired set pressure (otherwise factory set at mid-range) and whether RNCE construction is required
Only pages 1-2 of the bulletin were used; the spring and parts pages (3-4) were not reviewed for this listing. Bulletin issues to confirm with the factory: the highest spring range is given as 0-125 psi / 60-125 psi in the specifications but 60-100 psi in the ordering table; and a "** Limited by diaphragm" footnote has no matching reference.
Pricing and lead time are quoted per configuration. Send the model code (or your application details), product, flow range, and pressure/temperature to Flow Measurement Services for a quote. Specifications summarized from Smith Meter (INVALCO) bulletin SSIN055 Rev 0.1 (1/19) - pages 1-2 read; confirm current data with the factory before ordering.
Smith Meter (formerly FMC Technologies / TechnipFMC Measurement Solutions), now manufactured by Guidant. Flow Measurement Services supplies and services Smith Meter equipment.