The INVALCO Series 423 is a diaphragm-operated, two-way, non-freeze liquid dump valve for high-pressure separators and other vessels where freeze-ups are a problem. The valve threads into the vessel and its trim and seat sit fully immersed in the liquid, preventing freeze-up at the plug and seat. Hammer union body cover for quick repair and replaceable trim (RNCE available). Typically paired with an INVALCO Flextube liquid level control on a Monotube separator.
Key specifications
- Body: Low carbon steel
- Connections: Vessel 2" MNPT; inlet tube 1" FNPT; outlet 1" FNPT
- Body cover: Steel union
- Diaphragm operator: Steel, 26 sq. in., nylon-reinforced Buna-N; direct acting (normally closed) standard; 70 psi max. recommended operating, 100 psi max. containment
- Maximum working pressure: 3,000 psi
- Temperature: -20 to 250 °F
- Stem: 303 stainless steel
- Packing: Non-lubricated Buna-N
How to specify / order
- 2" x 1" model NFDSA-130-423, 1/4" taper trim, Cv 1.7, 3,000 psi, 416 hardened SS trim part number P534845, 45 lb (316 SS and carbide trims are shown as not available for this size)
- Per the bulletin, specify model number, part number and trim description; part numbers apply only to the exact configuration described
- State if RNCE (sour service) construction is required
Only pages 1-2 of the bulletin were used; the parts pages were not reviewed for this listing.
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 SSIN061 Rev 0.1 (11/18) - 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.

