Sanitary spring-loaded check valve of the SMS system, fitted to prevent reverse flow in hygienic process lines in food, dairy, beverage and pharmaceutical plants.
Prices on request. Contact us for availability and quotations.
The valve holds a guided disc against a seat with a light spring. Forward flow lifts the disc off the seat as soon as the pressure difference exceeds the cracking pressure; reverse flow, or the loss of forward flow, lets the spring close it. There is no external moving part and no operator: the valve protects a pump, a filler or a CIP set from backflow and from the contamination that backflow carries.
The cracking pressure is set by the spring and falls as the size rises, because the disc area grows faster than the spring load. That matters when the valve is fitted on a gravity line or downstream of a low-head pump, and it is the figure to confirm against the duty rather than assume.
Wetted parts are austenitic stainless steel to ISO 2604-1, in practice AISI 316L (1.4404), with the spring in a spring grade such as AISI 302 and non-wetted parts in AISI 304. The product-contact finish is Ra 0.8 µm or better. The seal is chosen for the product: EPDM for dairy, water and CIP but not for oils and fats; NBR where fats and oils are carried; FKM or PTFE for aggressive duties or higher temperatures.
State the nominal size, the connection system and end form, the seal material, and whether the disc is to be perforated to give a minimum circulation and avoid a stagnant pocket. Mount the valve so the disc is guided in the intended orientation; a check valve installed the wrong way round in a hygienic line is both a process fault and a cleaning fault.
| How to Order | Both the SMS and the DIN system are stocked. This is the SMS valve, ordered in inch sizes — 1", 1½", 2" and so on; the DIN valve is the other listing. The sizing convention is what tells them apart on an order. |
|---|---|
| Valve Type | Spring-loaded, guided-disc check valve — non-return only, with no external operator |
| Connection System | SMS system — the valve is dimensioned for SMS tube. End form (weld, male threaded SMS union or clamp ferrule) must be stated; it is not fixed by the name |
| Size Range | SMS sizes 1", 1½", 2", 2½", 3" and 4" on tube outside diameters of 25.0, 38.0, 51.0, 63.5, 76.1 and 101.6 mm |
| Connection Pressure Class (SMS union) | Where the valve is joined by an SMS union, the union system's nominal pressure class is 6 bar at ambient temperature. This is the class of the union, not a tested figure for the valve — this rates the union, not the valve; obtain the valve's own pressure rating for the size ordered |
| Wetted Material | Austenitic stainless steel selected from ISO 2604-1; specify AISI 316L (1.4404) wetted, a spring grade such as AISI 302 for the spring, and AISI 304 (1.4301) for non-wetted parts |
| Surface Finish | Ra < 1.0 µm on finely finished product-contact surfaces; Ra ≤ 0.8 µm is the finish usually quoted for hygienic service |
| Gasket | Natural or synthetic rubber, compatible with the product and the cleaning fluids and imparting no odour or taste. EPDM, NBR, VMQ, FKM or PTFE to be specified |
| Applicable Hygiene Standard | 3-A 58-02 Vacuum Breakers and Check Valves is the applicable class for this type of equipment. The goods are not asserted to carry the 3-A Symbol |
