Sanitary Control & Pressure-Reducing Valves: DCX3, AVX1 and Food-Safe Safety Valves

A sanitary on/off valve has only two states — fully open or fully closed. A sanitary control valve is different: it opens the valve to intermediate positions to maintain a process parameter (flow rate, pressure, level) at the set value. To achieve this, the valve requires a positioner that receives a 4-20mA analog signal from the control system and translates it into the corresponding plug opening position.

In food and pharmaceutical environments, control valves must still comply with all the same hygienic requirements as on/off valves: SS316L body, smooth surfaces, dead-leg free design, food-grade seals, and clean-in-place capability. The difference lies in proportional control capability, which enables the production line to remain stable under varying loads — for example, maintaining UHT sterilization pressure, stabilizing flow rate into a filling machine, or controlling steam pressure into a heat exchanger.

Definox developed the control version based on the familiar DCX3 valve body. The DCX3 REGUL version is fitted with a positioner that receives a 4-20mA signal, allowing the valve plug to stop at any intermediate position to maintain flow rate or pressure at the set value. Because it shares the same body architecture as the on/off series, the DCX3 control valve inherits all hygienic characteristics: SS316L, dead-leg free, self-draining, food-grade seals, and CIP/SIP capability.

The pneumatic actuator combined with the positioner enables fast valve response to signals from a PLC or PID controller. When position feedback and CIP automation integration are required, the valve can be fitted with a Sorio actuator head (AS-i/IO-Link protocol, IP67 protection rating). This configuration is suitable for continuous control points in dairy, beverage, brewing, and food processing plants — where process parameters must remain stable while meeting 3-A sanitary standards.

Overpressure can damage seals, deform tanks, or cause safety incidents; conversely, negative pressure (vacuum) during tank draining or cooling can also collapse equipment. Definox’s sanitary pressure-reducing/safety valve handles both directions: it opens to relieve pressure when the threshold is exceeded and admits air when pressure drops below a safe level. The operating range of 0.2–13 bar covers the majority of requirements for process tanks and sanitary pipelines.

Unlike conventional industrial safety valves, food-grade safety valves must maintain hygienic integrity at the discharge point itself: SS316L contact surfaces, clean discharge path, food-grade seals, and CIP cleanability. This ensures the valve both protects equipment and does not become a microbial accumulation point on the production line.

AVX1 is a sanitary valve dedicated to two functions: metering and venting. In the metering application, the valve opens and closes decisively in a timed sequence to deliver a precise quantity of ingredient or additive into the flow stream. In the venting application, AVX1 allows safe gas release from pipelines or tanks — preventing air pockets that cause measurement errors and preserving the hygienic integrity of the vent port. The valve is 3-A sanitary standard compliant and manufactured in SS316L, consistent with the rest of the range.

When used together with the DCX3 control valve and the pressure-reducing/safety valve, these three products cover the complete “control — protection” function group of a sanitary production line: DCX3 maintains stable process parameters, the pressure-reducing valve protects against overpressure and vacuum, and AVX1 handles metering and venting. All share the same design philosophy of dead-leg free construction, self-draining, and clean-in-place.

Selecting the correct valve type depends on the control task. When a process parameter needs to be held stable in real time, choose the DCX3 control valve with a 4-20mA positioner. When the task is to protect equipment from overpressure or vacuum, the sanitary pressure-reducing/safety valve is the appropriate choice. When precise ingredient delivery or pipeline venting is required, AVX1 serves both purposes. The table below summarizes how to match requirements with valve type.

All configurations are based on SS316L and 3-A sanitary standards, so the valves can be seamlessly integrated with the rest of the sanitary production line without disrupting the CIP/SIP sequence.