Oxygen Depletion Monitor for MRI rooms
Guards against suffocation hazards due to cryogen leakage

  • Low Oxygen alarm at 19.5% v/v
  • Field replacable pre-calibrated sensors
  • 3 built in relays for Alarm 1, 2 and Fault
  • Power over Ethernet (PoE) communication and power platform
  • Keypad Interface and remote Web Browser Ethernet IP interface
  • Password protected set up
  • Bright LEDs and intuitive menu
  • Isolated 4-20 mA Analog Output with fault and event reporting
  • Modbus/TCP Ethernet for easy connectivity to all control and alarm systems ports for control connectivity and service interaction
  • Robust extractive pump system (2 year lifetime) sampling up to 30m (~100ft)
  • CE marked - total immunity to RFI

MRI machines contain powerful super conducting magnets that are cooled by liquid helium. The storage and MRI oxygen depletionshandling of liquid helium and liquid cryogen presents a safety hazard within the MRI environment. Helium is a colorless and odorless gas not directly detectable by humans. In the event of a cryogen leak the air and hence the oxygen in the room can be rapidly displaced by the helium or nitrogen gas thus reducing the ambient oxygen concentration and posing a suffocation asphyxiation hazard to personnel in the MRI room. For this reason it is recommended and often mandated that MRI rooms be monitored with an oxygen depletion (deficiency) monitor. The MIDAS O2 is designed for this purpose. It comprises a sensitive oxygen sensor and electronics package with a remote sensing system. The instrument must be located outside the range of the MRI magnetic field environment. The atmosphere is constantly sampled by a length of tubing that runs from within the MRI room to the instruments sampling port. The MIDAS O2 is self contained with a built in sampling pump alarm relays, and analog and digital alarm outputs. The unit is small in in size and its easy access metal chassis design makes it simple to install even when space is at a premium. The unit can be wall mounted using mounting points on the back of the chassis. An optional L bracket provides a free standing mount which can be secured to a horizontal surface. A duct adaptor is provided should it be necessary to connect the sample tube line into an air duct.mounting bracket for MIDAS 02

MIDAS O2 includes various power and communicationsoptoins as standard including 3 on-board relays, 4 - 20mA analog output, Modbus/ TCP Ethernet digital outputs, as well as the innovative Power over Ethernet (PoE) protocol - a single Ethernet connection for all power, control and communication requirements. It can be run as standalone alarm system or integrated with PLC and FieldBus systems.

MIDAS O2 offers lower cost of ownership benefits for increased MRI safety through a combination of extended sensor calibration periods, flexible communications architecture, and patented diagnostics that monitor sensor performance and flow control. MIDAS O2 will monitor points up to 30m (100 feet) away from the transmitter and flow rates are regulated automatically using patented control technology to ensure error free gas sensing operation.

For an MRI room, the sensor must be located outside to exclude any metals from the environment. A sampling pump draws air from the MRI zone and delivers it to the oxygen sensor. Cryogen leakage can cause rapid suffocation when concentrations are high enough to reduced oxygen concentration levels below 19.5%.


Transmitter Dimension (unit with Sensor) 120mm (H) x 63mm (W) x 150mm (D) Weight: (unit with Sensor) 0.8Kg
Power Requirements Operating Voltage 24V DC Nominal +/- 10% Operating Voltage with Power over Ethernet (PoE):
36 - 57 VDC via PoE, 48V DC Nominal
Power Consumption Transmitter Unit: ~ 5.0W
Outputs Visual: Alarm, Power and Fault lights as well as back lit LCD
display with all gas readings and events
Relays: 3 relays for Alarm1, Alarm 2 and Fault rated 1.0A
@ 30VDC or 0.5A @125VAC;
configurable NO or NC, latched or unlatched
Analog: 2 wire isolated, 0 - 22mA, Sink or Source Digital : Modbus / TCP Ethernet / Power over Ethernet (PoE)
Service Port RS232C / PPP protocol
Sampling Distance Tubing Length: Up to 30m (100 feet) Ambient Point Monitoring: In line air filter recommended
Tubing Requirement Exhaust Length Up to 30m (100 feet)
Sample: 6.35mm OD (1/4”) x 3.18mm (1/8”), FEP, 30m (100 feet) maximum dependant on gas type
Operating Temperature 0˚ C (32˚ F) to 40˚ C (104˚ F)
Wiring Requirement 4-20mA/DC Power/Relays: 14 AWG Maximum Digital: CAT 5 cable or equivalent, RJ45 connector
Gas Concentration Display & Interface Instrument: 4-digit alphanumeric display with separate measurement units, flow rate bar graph and other icon driven indicators. 4 button membrane keypad Remote Interface: PC / PDA Internet Browser access via Ethernet or other Bus system
Response Times Flow Rate: 500 mL/min Transport Time: 2 - 30 seconds maximum
Warranty Transmitter Unit: 1 year
Sensor Cartridge: 1 year standard; 2 year with extended warranty program
Expected Lifetime of Pump: >2 years
Certification & Specification European: CE marked; meets EN 50270:1999 (Type2)
and EN 55011:2000
Environmental: ETL approved UL 61010B and CSA-C22.2
No. 1010.1-92
Performance: Designed to meet with UL 2075 (pending 2004)
Electrical: >IEEE 802.3af-2003

Ordering Information

MIDAS-K-O2X MIDAS O2X (O2) Cartridge and Transmitter Kit, includes built in wall mount and duct adapter
Oxygen Range(O2): 0.2-25% v/v - default alarm 19.5%
MIDAS-A-032 Vertical mounting L bracket kit (The standard instrument can be wall mounted via 2 screws through the backplate of the housing - the optional L bracket provides a means of supporting the unit on a horizontal surface note that the utilities pass through the bottom of the housing) $133.00
1283k1090 Spare Duct adapter for 1/4" O.D tubing for 4-16" round ducts, allows connection of sample line tubing thru the wall of a duct $56.00
TB 1/4" Polypropylene tubing for sample line - 100 ft $125.00