What Is an Area Valve Service Unit and Why Hospitals Need It

What is an area valve service unit?

An AVSU, also called a medical gas zone valve box, contains one isolating valve for each gas supplied to a zone, usually with a pressure indication for each line and a test point for the engineer. It sits between the main distribution pipework and the branch serving the area.

Without zone valves, any fault, leak or planned works on a branch would require isolating a large part of the hospital. With them, engineers shut off only the affected area, and staff can react to an emergency such as a fire or a pipe fracture without losing gas elsewhere.

Area valve service unit function and what it is used for

The function of an AVSU is isolation. It is used in three situations: emergency shut-off, for example in the event of a fire or serious leak; planned maintenance or extension of the pipeline downstream; and pressure testing and commissioning of one zone at a time.

The manufacturer of the digital MZ Liberec unit stresses that it is intended solely for emergencies and maintenance, not for routine use. Closing it cuts off all outlets downstream, so closing a valve for an ICU or theatre must be coordinated with clinical staff and an alternative supply must be ready.

Features of the digital AVSU

The digital AVSU from MZ Liberec shuts off the gas flow to the next distribution area. Pressure sensors warn of non-standard pressure in the area, and an LED display shows current pressure values and OK or error status. Up to six gas lines can be connected.

The unit has an aluminium body with an antibacterial surface and an emergency lock that can be broken open. It is available for built-in or wall-mounted installation, with an optional alarm system, and can be connected to the MZU II monitoring device. An analogue version with pressure gauges is also offered.

• Up to 6 gas lines
• LED display of pressure and status
• Pressure sensors warn of abnormal pressure
• Break-open emergency lock
• Built-in or wall mounting, optional alarm

Where to place AVSUs

Place a unit in a corridor or other accessible, clearly marked location outside the zone it serves, so staff can reach it quickly without entering a fire or contaminated area. Each critical department such as operating theatres, ICU and recovery usually has its own unit, and a floor or ward may have another. Label the unit with the rooms it controls.

Design the zoning together with the alarm scheme. Area alarm panels should show the status of the supply to the same zone. A touchscreen device such as the MZU II can display pressure for 1 to 12 gases and connect to an AVSU.

Specification and maintenance checklist

When specifying, check the number of gas lines, the gases, the connection sizes, the valve type, the means of pressure indication, the lock arrangement and the standard to which the unit is built. Standards usually referenced in projects include ISO 7396-1 and HTM 02-01. Make sure the labelling and gas identification are clear.

In service, operate valves periodically under a controlled procedure, inspect the lock, verify the pressure indication against a calibrated gauge and keep a record. Beckfinity supplies MZ Liberec valve units and alarms in the UAE; to discuss a project, contact our specialists.