A valve pressure test bench is bought on its headline numbers — maximum pressure, largest valve size — but those two figures alone do not tell a buyer whether a valve will actually fit and test correctly on the machine. Before comparing prices, check four numbers against the valves you test most often.

1. Valve size range — both ends matter

A bench is rated for a span, not a single size. The SYTW400/4-32, for example, covers DN50–400; the SYTW300/16-32 covers DN80–300; the SYTW600/10-32 covers DN300–600. A bench whose lower end is above your smallest valve cannot test it, and one whose upper end is below your largest valve cannot clamp it. List your smallest and largest valves first, then match the span.

2. Test pressure is per diameter, not one number

The equipment maximum is only the top of a stepped rating. On the SYTF400/10-38, the equipment maximum is 40.0 MPa, but the applicable test pressure steps down as the valve grows: 37.5 MPa for DN100–150, 22.5 MPa for DN200–250, 15.0 MPa for DN300, and 9.6 MPa for DN350–400. The SYTW300/16-32 shows the same pattern at a lower level: 31.5 MPa for DN80–150, 22.5 MPa for DN200, and 16 MPa for DN300. Always ask for the per-diameter pressure table, not just the maximum.

3. Clamping force must match the test pressure

The force that holds the valve shut during a pressure test scales with size and pressure. Across the horizontal test bench range, clamping force runs from 90 ton-force (approx. 883 kN) on the SYTW500/3-32, through 170 ton-force (approx. 1,667 kN) on the SYTW300/16-32, to 350 ton-force (approx. 3,432 kN) on the SYTW600/10-32. The SYTF400/10-38 flange-clamping bench is rated at 185 ton-force (approx. 1,814 kN). A bench with too little clamping force for the pressure you test at will not hold a seal, whatever its size range says.

4. Face-to-face length and sealing-disc spacing decide the fit

Two valves with the same DN can have different face-to-face dimensions, and the bench must accommodate the longest and shortest in your range. The SYTW400/4-32, for example, accepts face-to-face lengths from 178 to 600 mm, with sealing-disc spacing from 150 to 700 mm. Measure your longest valve and your shortest valve, and confirm both against the bench's clamping length before ordering.

A short checklist before you buy: smallest and largest valve sizes; required test pressure at each diameter; clamping force at that pressure; longest and shortest face-to-face lengths. A bench that passes all four will test every valve in your workshop. One that passes only the headline maximum will test only some of them.