Is a high dew point a plant emergency?

Yes. HTM 02-01 (2026) lists dryness above −46 °C at atmospheric pressure as a plant emergency, together with receiver pressure 50 kPa below the standby cut-in pressure or above the cut-out pressure.

Which alarm colour means a pipeline problem?

Red. On the HTM 02-01 alarm signal status unit, a pipeline pressure fault is red, while plant fault, plant emergency and reserve low are yellow.

What alarms should a medical air plant have?

Q: Which faults should a medical air plant report, from compressor and dryer faults to dew point and pipeline pressure?

Under HTM 02-01 (2026), the NHS England guidance, a medical air plant should detect compressor faults, dryer faults, a plant emergency (receiver pressure 50 kPa below the standby cut-in or above the cut-out, or dryness above −46 °C at atmospheric pressure), a low cylinder reserve, and low or high pipeline pressure.

Which faults should a medical air plant report, from compressor and dryer faults to dew point and pipeline pressure?

What the plant monitors

HTM 02-01 (2026) lists the faults that the monitoring system of a medical air compressor plant should detect:

For each compressor: control circuit failed, motor tripped, after-cooler temperature high, compressor temperature high, compressor failed to go on load, and activation of other safety devices supplied by the manufacturer.
For each dryer unit: dryer failure and pressure fault.
Plant emergency: receiver pressure 50 kPa below the standby cut-in pressure, receiver pressure 50 kPa above the cut-out pressure, or dryness above −46 °C at atmospheric pressure.
Cylinder reserve: pressure in the duty bank below 50% of normal cylinder pressure.
Pipeline: low pipeline pressure and high pipeline pressure.

The HTM says that when the duty dryer fails on dryness or pressure, the dryer control unit should change over automatically to the standby dryer, activate the appropriate fault indicator and its volt-free contacts, and stay in that mode until the fault has been rectified.

How the alarms are shown and passed on

At the plant, the HTM says the status indicators should show green for mains supply on and yellow for each compressor fault, and for each dryer a yellow dryness fault and a yellow pressure fault. The alarm signal status unit should display green for normal, yellow for plant fault, plant emergency and reserve low, and red for a pipeline pressure fault. The HTM says the conditions other than normal should be transmitted to the central alarm system, where its Table 24 shows a fault on compressors or dryer that does not compromise air quality or outlet pressure as plant fault, and multiple faults that affect the air supply as plant emergency. The plant alarm should be a separate unit in the plantroom, and its cabling should be monitored for open and short circuit. Volt-free contacts let a building management system (BMS) monitor the alarm conditions, but the HTM says the BMS should only monitor the plant and not control its functions, changes or isolations.

Where carbon monoxide fits

Carbon monoxide is not in the HTM 02-01 list of plant faults. The HTM covers it through quality control testing: terminal units should be tested for the absence of carbon monoxide, with a concentration not exceeding 5 ppm (v/v).

Other specifications

ISO 7396-1:2016, the international standard for medical gas pipeline systems, includes requirements for monitoring and alarm systems alongside supply systems, distribution and control systems. In Portugal, ACSS ET 03/2006 (revised in June 2024) asks for light and sound safety signalling on the medical air compressor plant and for the production system to be connected to the building automation and control systems.

Alarm outputs on ULTRAAR plants

The ULTRAAR SCA control panel gives a running signal, a failure signal and an hour meter for each compressor, and brings out all alarms on an interface for remote signalling; its ULTRASEC refrigeration dryer has a dew point indicator and a dry contact alarm. The ULTRAAR SC datasheet lists 24-hour remote monitoring and connection to a management system or central alarm network, and the ULTRAMED treatment unit has a low dew point indicator alarm.