Sandwich Plate Isolation Valve


	The Challenge: Hydraulic systems with a large number of control elements are susceptible to malfunctions. If a solenoid valve in the central hydraulic system of a rolling mill failed, the controlled component would need to be manually operated or production would be halted to change the valve. This replacement makes it necessary to depressurize the system, prop up external loads supported by the cylinders and drain the fluid from the lines to the cylinders. Once the valve has been changed, the lines would have to be refilled and bled. Shutdown times for such involved work cause considerable downtime costs, especially in large plants.
	The Solution: With the use of the Rötelmann sandwich plate, which is bolted separately to the manifold, all channels through the plate can be blocked and the directional control valves can be replaced without having to depressurize or drain lines and without affecting the other control units on the same manifold. All the ports are open during normal operation and the operating handle can be removed to prevent unauthorized actuation.
	Advantages: Full bore design causes minimal pressure drop Considerable reductions in hydraulic system downtime. The system does not need to be drained, refilled and bled Simplifies replacement of flushing plates at system start-up Simple retrofit, mounting and porting patterns in D03, 05, 07, 08, and 10 Pressure can be maintained in cylinders so that the supported loads do not need to be shored up