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Directional control valves
Directional valves determine where pressurized oil is routed, which cylinder or motor gets flow and in which direction, and they are the component that actually makes a hydraulic circuit do useful work rather than just build pressure. Actuation can be manual, solenoid operated for remote or automated control, or pilot operated where a smaller control signal shifts a larger main valve spool. Match actuation type to how the circuit is actually operated, a manually shifted valve has no place on a circuit that needs remote or automated control.
Pressure relief valves
Relief valves protect the system from dangerous overpressure by opening a bypass path once system pressure exceeds a set threshold, and they are a non negotiable safety component on any hydraulic circuit, not an optional extra. Confirm the relief setting matches the circuit’s actual working pressure with an appropriate safety margin, a relief valve set too high defeats its own purpose, and one set too low causes nuisance bypass under normal operating loads.
Proportional and flow control valves
Proportional valves allow variable, precisely controlled flow rather than simple on or off switching, which matters for applications needing smooth, modulated motion, crane load positioning, precision lifting, or any circuit where an abrupt full flow shift would be a safety or control problem. These valves cost more than simple directional valves and need a control signal source, so specify them where the application genuinely needs graduated control, not as a default upgrade.
Rig site and offshore valve actuation
On oil and gas rig sites, hydraulic power units store pressurized oil in accumulators specifically so a valve can be shifted immediately on demand rather than waiting on pump response time, a pattern used for wellhead and blowout preventer valve actuation where response speed is a safety requirement, not a convenience. Offshore platforms and FPSO vessels commonly run valve remote control systems that let a central control station shift dozens of valves hydraulically from one location, communicating with the HPU over a SCADA interface rather than requiring a technician at each valve.
Any hydraulic valve installed in a Class I Division I classified rig site area needs certification confirming it is sealed and rated against igniting flammable gas or vapor. Offshore and marine valve installations similarly need ATEX or DNV-GL certification for the corrosive, wet, and often classified environment they operate in. Neither certification can be assumed from a valve’s general industrial rating, confirm it specifically before ordering for a classified area.
Selector valves on forklifts
On forklifts specifically, the selector valve directs hydraulic flow between the mast lift function and the tilt or attachment function, and a worn or failing selector valve shows up as sluggish or unresponsive switching between these functions even when the pump itself is healthy. BPS stocks Hyster forklift selector valves directly, including part 157B4092 and the 157B4792 variant.
Relevant BPS products. Selector Valve 157B4092 and Selector Valve 157B4792 for Hyster forklifts, alongside the wider hydraulic pumps and valves range for cranes, heavy equipment and industrial applications.
What to send with your RFQ. Valve type needed, directional, relief or proportional, port configuration, actuation method, required pressure rating, and hazardous area certification if the valve is going into a classified rig or offshore location.
Common selection mistakes
- Specifying a simple directional valve where the application actually needs proportional, graduated control
- Setting a relief valve pressure without confirming it against the circuit’s real working pressure and safety margin
- Installing a general industrial valve in a Class I Division I or offshore classified area without confirming hazardous area certification
- Assuming a selector valve fault is a pump fault, when sluggish function switching on a forklift often points to the selector valve first
Frequently Asked Questions
What is the difference between a directional valve and a relief valve?
A directional valve controls where pressurized oil goes, which function or cylinder receives flow. A relief valve is a safety component that opens a bypass path once system pressure exceeds a set threshold, protecting the circuit from overpressure damage.
Do hydraulic valves need special certification for oil and gas rig sites?
Yes. Any valve installed in a Class I Division I classified area needs certification confirming it is sealed and rated against igniting flammable gas or vapor. This cannot be assumed from a general industrial pressure rating.
What does a valve remote control system do on an offshore platform?
It lets a central control station shift multiple valves hydraulically from one location, communicating with the hydraulic power unit over a SCADA interface, rather than requiring a technician to operate each valve manually on site.
Source referenced in this guide: Flickinger Machine, Hydraulic Equipment Guide for Oil and Gas Operations
Need help identifying the correct part?
Send the equipment make and model, existing part number, required quantity and available photos or technical documents.
Related Guides
- Hydraulic Pump Types and Brands Guide
- Hydraulic Motor Selection and Troubleshooting Guide
- Hydraulic System Contamination and Component Failure
Editorial note. Valve types, rig site accumulator and valve remote control patterns, and Class I Division I hazardous area requirements are drawn from independent technical sources on oil and gas hydraulic equipment and marine hydraulic systems. BPS’s Hyster Selector Valve 157B4092 and 157B4792 listings are pulled directly from BPS’s own live hydraulic pumps and valves category page.