Safety and Pressure Relief Valves
Shut-Off, Control and Safety Valves
A safety relief valve opens once the circuit reaches its set pressure, releases just enough medium to bring the pressure down and closes again. It protects expansion vessels, heat exchangers and cooling manifolds against excess pressure when the water-glycol mixture heats up or a control valve sticks. The group lists 8,087 items, but that number is no argument for selection: it covers a handful of designs offered in fine increments of set pressure. One cooling circuit needs one or two of them.
Three figures lead to the right valve. The set pressure sits above the highest working pressure and below the limit of the weakest component in the circuit; stock covers steps from 1.1 through 2.00, 3.20, 4.60, 5.00, 8, 11.00, 17.60, 20.00 and 22 up to 25 bar. Connection sizes run from G 1/4 through G 3/8 and G 1/2 to G 3/4 and G 1 1/4 with DN 8 or DN 10 seats. On material the rule is simple: stainless 1.4401 without restriction, brass only in a single-alloy circuit.
What to establish and what the range offers
| Figure | What to check | Available |
|---|---|---|
| Set pressure | highest working pressure plus margin, below the limit of the weakest component | steps from 1.1 to 25 bar, among them 2.00 / 3.20 / 4.60 / 5.00 / 8 / 11.00 / 17.60 / 20.00 / 22 bar |
| Connection size | thread of the pipe or connection boss at the mounting point | G 1/4, G 3/8, G 1/2, G 3/4, G 1 1/4 |
| Seat size | quantity to be discharged in a fault, seat design | DN 8 and DN 10, HSV high-capacity version for larger rates |
| Material | compatibility with pipe material and water-glycol mixture | stainless 1.4401, brass, nickel-plated brass |
| Documentation | inspection duty of the installation, record of the setting | SV and HSV series listed as TÜV safety valves |
- Protecting closed water-glycol circuits against pressure rise from heating up
- Protecting expansion vessels and pressure maintenance units in the cooling circuit
- Relief downstream of pressure reducers in the make-up line
- Protecting heat exchangers and manifolds with a limited pressure rating
- Relief of isolated pipe sections in which trapped medium can expand
- Replacement and retrofit of due valves at the recurring inspection of the plant
