Can the Controlled check valve used in hydraulic systems, type FPD be used with fluids other than hydraulic oil and what compatibility issues exist?

Controlled check valve used in hydraulic systems, type FPD can be used with fluids other than hydraulic oil only if those fluids are compatible with its materials: galvanized steel body, hardened steel piston and NBR seals. NBR is not resistant to many fluids (strong polar solvents, ketones, some esters, hot water above 80â90Â°C, glycol-based fluids at high temperature can cause swelling/hardening). Galvanized steel may corrode with water-based fluids, salty or acidic media; hardened steel is better but can corrode without proper protection. Temperature limits (-20Â°C to +100Â°C) also restrict use with very hot or very cold fluids. If your fluid is synthetic hydraulic fluid, mineral oil, or standard petroleum-based oils within the temperature range, compatibility is likely acceptable; for water-glycol, phosphate esters, biodegradable esters, solvents or aggressive chemicals, verify NBR and plating compatibility or choose alternative seal materials (e.g., FKM, EPDM) and corrosion-resistant construction. Also confirm viscosity and contamination levels to ensure valve opening pressure and function.

How does the Controlled check valve used in hydraulic systems, type FPD behave under thermal expansion and pressure spikes?

Controlled check valve used in hydraulic systems, type FPD behaves predictably under thermal expansion and pressure spikes due to its design, materials and specified operating limits. Thermal expansion: - Body and piston materials (galvanized steel body, hardened steel piston) have similar thermal expansion coefficients, so differential expansion is limited, preserving alignment and sealing integrity across the rated range. - NBR sealing remains effective between -20Â°C and +100Â°C; near the upper limit NBR softening may slightly reduce spring-loaded seating force, potentially lowering sealing stiffness but not causing leakage under normal conditions. Below -20Â°C NBR hardening can reduce elasticity and increase the risk of imperfect sealing. - Overall, within -20Â°Câ¦+100Â°C thermal growth will cause minimal change in clearances; the valve will maintain function and locking behavior if installed and operated within temperature spec. Pressure spikes: - The valve is designed as a hydraulic lock with an opening pressure of 3 bar (0.5 bar for 3/4" thread). Under transient pressure spikes below the opening threshold in the locked direction, the valve remains closed and prevents unintended actuator movement. - If a pressure spike in the allowed flow direction exceeds the opening pressure, the piston will lift and allow flow; short spikes above opening pressure will momentarily open the valve and then re-seat when pressure falls below the setpoint. Repeated high-frequency spikes may cause wear on the hardened piston and NBR seal over time. - Extremely high overpressure beyond design limits risks seal extrusion or damage to the body/piston; the valve does not provide overpressure relief and should be used with appropriate system protection (relief valves). - For the 3/4" size, lower opening pressure (0.5 bar) means it will respond/open more readily to spikes in the permitted direction. Summary: Within specified temperature (-20Â°C to +100Â°C) and pressure ranges, Controlled check valve used in hydraulic systems, type FPD maintains locking behavior under thermal expansion and resists unintended movement during pressure spikes up to its opening threshold. Outside these specs or under excessive spikes, sealing degradation or mechanical damage can occur; system relief/protection is required.

Controlled check valve used in hydraulic systems, type FPD

Q: What is the correct installation orientation for the Controlled check valve used in hydraulic systems, type FPD to ensure proper locking and permitted flow directions?

For correct installation of the Controlled check valve used in hydraulic systems, type FPD, orient the valve so that the permitted flow directions match the system piping: install it to allow flow V1 â C1 (with the complementary path C2 â V2) or V2 â C2 (with complementary C1 â V1). The valve must be mounted with its inlet and outlet ports aligned to those port labels in the hydraulic schematic so the piston and sealing face operate as designed (galvanized steel body, hardened steel piston, NBR seal). Ensure the valveâs flow direction arrows (or port markings) correspond to VâC flow; reversing the valve will prevent proper locking and may allow unintended actuator movement. Consider the specified opening pressure (3 bar; 0.5 bar for 3/4" thread) when placing the valve in the circuit so unintended bypass does not occur. Install in a clean, accessible location, avoid excessive vibration or misalignment, and observe temperature limits (â20Â°C to +100Â°C).

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Additional information

Material	CS – steel (cast iron)

Controlled check valve (hydraulic lock) type FPD used in hydraulic systems as a safety element against unintentional movement of double-acting actuators (retraction / extension of the piston rod). Permissible flow directions: V1 → C1 (and simultaneously C2 → V2), V2 → C2 (and simultaneously C1 → V1). Material: galvanized steel (body), hardened steel (piston). Sealing: NBR. Opening pressure: 3 bar, for thread size 3/4″ – 0.5 bar. Operating temperature: from -20°C to +100°C.

List of product variants

Article number	Product variant name	DN	BAR	Availability	Actions
DC-FPD-04	FPD GW 1/4" controlled check valve	-	350	In stock	Enquiry
DC-FPD-06	FPD GW 3/8" controlled check valve	-	350	In stock	Enquiry
DC-FPD-06-30L	FPD GW 3/8" controlled check valve, compact	-	350	In stock	Enquiry
DC-FPD-08	FPD GW 1/2 controlled check valve	-	350	In stock	Enquiry
DC-FPD-12	FPD GW 3/4" controlled check valve	-	210	In stock	Enquiry

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Controlled check valve (hydraulic lock) type FPD used in hydraulic systems as a safety element against unintentional movement of double-acting actuators (retraction / extension of the piston rod). Permissible flow directions: V1 → C1 (and simultaneously C2 → V2), V2 → C2 (and simultaneously C1 → V1). Material: galvanized steel (body), hardened steel (piston). Sealing: NBR. Opening pressure: 3 bar, for thread size 3/4″ – 0.5 bar. Operating temperature: from -20°C to +100°C.