Unlike industrial NFPA (National Fluid Power Association) hydraulic valves, mobile valves have no standards, no common mounting and no direct interchange. These valves can be a simple, single-spool Monobloc-style valve or a more complicated 10-spool sectional valve stack. The question is… how do you replace a valve that you might already have in service or what parameters are required to specify a new valve.
Initial Check List:
- What is the flow rate from the pump feeding the valve or multiple valve stack
- Is it an open center circuit or closed center
- How many functions (spools) are there
- What are the functions for each spool, cylinder spool, Motor spool
- What is the relief valve and pressure setting (if required)
- What is the maximum working pressure
- Port size, inlet/outlet working ports, related to flow rate
- Operator, manual lever, solenoid or both
These are just a few of the many alternatives that may be involved. Mobile valves can have many more options built into the body of the valve section, inlet, outlet or mid-inlet sections. It’s very common to have individual port reliefs in all, or selected sections, set at different pressures.
Other more complicated options could include:
- Pre/Post compensated flows rates at each section
- Power-beyond, pressure limiting, stroke adjustments
- On/off solenoids
- Proportional controls
- Load sensing