DPC1-10 Series Inline Double Pilot Operated Check Valve, Ports

In lock valve circuits, a pilot operated check valve is used to lock a cylinder without leakage while the control valve sits in neutral. It will allow flow to the cylinder, then block reverse flow until pilot pressure is applied to unlock the circuit, which helps keep a load from moving when the pressure source is inactive.

Lock valves are built exactly for that situation. When your control valve sits in neutral, this valve blocks reverse flow from both sides of the cylinder with no leakage, so the cylinder holds its position. The key thing to know is that a 4-way control valve is required in the circuit, even on single acting setups, because the pilot circuit needs a path to apply unlocking pressure when you want the cylinder to move again. As long as your control valve has a free-flow motor spool, pressure won't build up between the lock valve and the control valve, which is a common problem people run into.

For the blind end of a double acting cylinder, the formula works like this: take the blind end locked pressure and divide it by the quantity of 4.0 minus the rod end locked pressure divided by the ratio of net rod area to total cylinder area. More simply put, the rod area ratio is calculated as cylinder area minus rod area, all divided by cylinder area. The 4:1 pilot ratio built into this valve is what drives that math. For the rod end, the same structure applies but you swap the blind end and rod end values in the formula. Run your actual cylinder dimensions and locked pressures through both and you'll know exactly what your pilot circuit needs to deliver.

In a lock valve circuit, the DPC1-10 is meant to lock a cylinder without leakage while the control valve sits in neutral. It allows flow to the cylinder, then blocks reverse flow until pilot pressure is applied to unlock it, using a 4:1 pilot ratio.