The Opti-flow CNC 380 series are a low pressure PVRV breather valve available in a variety of configurations to suit your needs. All the CNC 380 series of valves are also available in both weight loaded and spring loaded on both the pressure and vacuum giving valve optional settings from 2 Mbarg to 500 Mbarg on both the pressure and the vacuum

Direct acting pressure / vacuum relief valves (also known as breather valves, conservation vents, or safety vents) are low pressure devices specifically designed to protect tanks, process systems and equipment from excessive pressure and vacuum.

As well as providing the primary layer of protection for tanks and process systems, pressure/vacuum valves also minimise emission losses of gases or vapours, thus protecting the environment and providing significant financial savings.

The range includes pressure only, vacuum only and combined pressure/vacuum valves, all available with flanged outlets or vented to atmosphere.

Pressure / vacuum relief valves are used extensively on bulk storage tanks, including fixed roof tanks with floating covers, to minimise evaporation loss. The valves prevent the build up of excessive pressure or vacuum which can unbalance the system or damage the storage vessel.

Pressure and vacuum protection levels are controlled with weighted pallets or springs and can be combined to provide the required pressure/vacuum settings. It is common to combine pallet and spring systems in one unit i.e. pressure settings require a spring section, whilst the vacuum settings use the pallet method.

PRINCIPLE OF OPERATION

Motherwell pressure vacuum relief valve can be configured with both weight-loaded or spring-loaded pallets. Flow through the valve is controlled by the weight of the pallet or the spring force acting on the pallet to keep the device closed. when the pressure is below the set limit

Once the pressure or vacuum in the tank reaches the pallet closing force, the pallet will start to lift off the seat and allow flow through the valve.

Due to its air-cushioned sealing technology, Motherwell valves prevent emission losses until very close to the set pressure, and prevents air intake until very close to the set vacuum. Leakage rates are consistently better than allowed for in API2000 and ISO 28300 with certification provided on request

The geometry of the valves has been developed in order to optimise overall performance in terms of high flow capacity, set pressure, sealing and re-sealing.

The modular nature of Motherwell’s valves means they can be tailored to meet specific customer requirements: whether this is pressure or vacuum-protection only; or vapours and gases either piped-away or vented to atmosphere.

A weatherhood protects the pressure vent port and a mesh screen is fitted to prevent intrusion of foreign matter into the valve.

These are some of the options available for our Breather Valves.

Our free valve sizing service ensures you have the right valve for you tank, let us advise you on the best breather valve for your tank