LESER Type 310 Change-Over Valve

Overview

The LESER Type 310 is a change-over valve, a fundamentally different device from a spring-loaded safety valve even though it lives on the same protected line: its job is to let plant personnel switch flow between two parallel safety valves without ever leaving the system unprotected. Covering DN 25 to DN 150, PN 40 to PN 160, NPS 1 inch to 6 inch, and pressure rating classes #150 to #600, the Type 310 is built in cast steel or stainless steel to match the same service conditions as the safety valves it serves. Wherever inspection, testing, or maintenance intervals on a pressure relief system cannot tolerate any window of unprotected operation, a change-over valve like the Type 310 is what makes that guarantee possible.

Working closely with plant engineers in the region, Seven Star LLC proudly supplies the LESER Type 310 to plant engineering and maintenance teams across Oman and the GCC. Refineries, gas processing plants, and petrochemical facilities in and around Muscat, Sohar, and Salalah increasingly specify dual safety-valve arrangements with a change-over valve precisely so that statutory in-service testing and overhaul schedules never force an unplanned shutdown, and our instrumentation division stocks and documents the Type 310 to support exactly that operating philosophy.

Operating Principle

The LESER Type 310 is installed upstream of two parallel safety valves protecting the same vessel or line, and its internal mechanism is engineered so that at every point during the change-over stroke, at least one of the two safety valves remains fully connected and in service – the valve is designed such that it is mechanically impossible to isolate both safety valves simultaneously, whether by operator error or mechanical failure. Operators actuate the change-over via a handwheel or gear operator, redirecting inlet flow from the safety valve currently in service to the standby unit in a controlled sequence, so that the standby valve is brought fully online before the previously active one is isolated for inspection or maintenance.

Because the Type 310 itself carries no spring or relieving function of its own, it introduces no additional overpressure risk to the system; its only job is directing flow between the two live safety valves while preserving continuous coverage. This mechanical guarantee of continuous protection is what allows a plant to pull a safety valve for statutory testing, seat lapping, or full overhaul on a running process line, something that would otherwise require a full unit shutdown.

Engineering Design of the LESER Type 310

The LESER Type 310 body is available in cast steel or stainless steel to suit the process media and pressure class of the installation, sized across DN 25 to DN 150 and pressure classes PN 40 to PN 160 / #150 to #600 to match a broad range of safety valve pairs from small process branches up to substantial relief headers. The valve is typically operated through a geared handwheel mechanism that provides mechanical advantage for smooth, controlled actuation even on larger DN sizes and higher pressure classes, and its internal porting is engineered so the operator cannot inadvertently drive the mechanism into a position that shuts off both outlets at once.

Flanged connections on both the inlet and the two safety-valve-facing outlets allow the Type 310 to be installed directly between the protected vessel or line and a matched pair of safety valves, commonly LESER units from the same project scope, without requiring bespoke adapter spool pieces. Position indication and, where specified, interlocking or locking provisions are available so that maintenance procedures can formally verify and document which safety valve is currently in service before work begins on the isolated unit.

Plant reliability teams specify the LESER Type 310 for the guarantees below. Key features of the LESER Type 310 change-over valve include:

• Mechanically guarantees that at least one of two parallel safety valves is always in service, eliminating any window of unprotected operation.
• DN 25-150 size range covering pressure classes PN 40-160 and #150-#600 for a wide span of process applications.
• Cast steel or stainless steel body construction to match the safety valves and process media it serves.
• Enables safety valve inspection, seat lapping, or full overhaul on a live process line without a unit shutdown.
• Geared handwheel actuation for controlled, smooth switch-over even at larger sizes and higher pressure classes.
• Flanged connections designed to interface directly with a matched pair of safety valves.
• Position indication and optional locking provisions to formally verify and document which valve is in service.
• Carries no relieving function of its own, so it introduces no additional overpressure risk to the protected system.

Industrial Applications

The LESER Type 310 is specified on critical process lines where a scheduled or statutory safety valve inspection cannot be allowed to force a plant or unit shutdown – refinery crude and product lines, gas processing plant separators and compressor discharge headers, and petrochemical reactor and column overpressure protection systems where continuous operation carries significant commercial value. This is a common design philosophy at large-scale process facilities across Oman’s industrial base, including refining and petrochemical operations linked to the Sohar and Salalah economic zones, where planned turnarounds are carefully managed and unplanned downtime is costly.

With fast quotation turnaround and technical support, Seven Star LLC distributes the Type 310 to EPC contractors, plant reliability teams, and maintenance planners throughout Oman and the wider GCC, sizing and specifying the change-over valve alongside the paired safety valves it will serve. Our instrumentation division supports full documentation packages so that dual safety-valve arrangements with in-service testing capability can be designed in from the start of a project or retrofitted into an existing protection scheme.

Technical Specifications

The table below summarizes the core technical data for the LESER Type 310 change-over valve, confirming its role alongside the paired LESER safety valves it serves.

Request a Quote for LESER Type 310

Seven Star LLC is ready to process a formal RFQ for the LESER Type 310 change-over valve, with lead time confirmed at quotation for customers across Oman and the GCC. Technical datasheets are available for download, and our instrumentation division can advise on sizing the Type 310 alongside your paired safety valves to keep in-service testing and maintenance fully compliant without shutting down the protected line. With engineering support in Muscat, Seven Star LLC supplies the valve on request with manufacturer documentation and technical support – contact us today to specify or order the Type 310.

Browse the full LESER range or see more Safety Relief Valves products supplied by Seven Star LLC in Oman and the GCC.