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    Car Park Ventalation
    Co Sensor Calibration
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Car Park Co Sensor CalibrationCo Sensor Calibration - Car park Fan Control

Why Do You Need To Perform a Carbon Monoxide Sensor Calibration every Six Months?

First and Foremost, Co Sensor Calibration is a safety requirement when managing or owning buildings, Commercial, Residential, or Industrial.

Any Property which has a car park, without satisfactory natural ventilation, must ventilate the car park via mechanical means.

The Occupational Safety and Health Act, section 21, Ensures any Carbon monoxide-controlled ventilation system is regularly serviced, and records kept, ensuring CO levels do not exceed exposure standards. Carbon monoxide sensor test & calibration is an essential service.

What is Co or Carbon Monoxide?

Carbon Monoxide is a poisonous gas which is created when burning gasoline, wood, propane, charcoal or other fuel. It is a colourless, odorless, tasteless gas. Which is why you need specialized detectors and an extraction system.Technical and Essential Services maintenance and Repairs including Car Park Venatalation system and Carbon Monoxide sensor calibration every six months

How Does the Carbon Monoxide Sensor System Work?

In a nutshell, the gas sensor detects the gas (via a device which actually delipidates over time, hence the regular calibration) and sends a signal (4 – 20 Milliamp or 0- 10 volts DC) to a car park fan system controller.

The Controller will then start fans and if a Variable speed drive is detected, the controller will increase the speed of the fans subject to the amount of gas sensed and the set point of the controller

Typically, the Controller with have a start set point of around 8 ppm (parts per million) to start the fans, the fans will run for a minimum of 4 minutes. At 24 ppm the system and / or the fans should be 100%.

The sensor must detect zero ppm for at least 4 minutes, and the system has run for a minimum of 7 minutes, before the fans are allowed to deactivate.

An Alarm for high Co Concertation will be Annunciated at 35 ppm after 1 minute

What is a Varible Speed Drive (VSD)?Diagram for Car Park Fna Control for Carbon Monoxide

The VSW is used primarily to conserve energy, it creates a “soft start scenario for the fans reducing the current draw as compared to D.O.L (Direct on Line)

D.O.L will draw around three times the nominal run current at start up.

The VSD means less current draw and less wear and tear on the mechanical component of the fan.

It also means the fan may not have to reach 100% before all the Carbon Monoxide is ventilated out of the car park and the sensor returns to Zero.

This provide an Energy saving also.

Which Standard Governs the Car Park ventilation System

AS1668.2.-1991 section 4

Is it part of Essential Services?


As a company whom service Fire systems, Mechanical HVAC systems and electrical we offer this service, Co Sensor Calibration, as part of package or individually.

A Holistic Essential Service System

The Mechanical ventilation component (fans and duct etc) and the electrical Component (Controller, Switchboard and mains Power) and the fire system (the FIP will send a trip signal to the Mechanical Ventilation Switchboard when in Fire Mode) all link with the Car park ventilation system.

What is Involved in Performing a Six Monthly Test on the car park ventilation System?

  • Test Carbon Monoxide Sensors for operation via “Cal Gas”
  • Co Sensor Calibration with 100ppm “Cal Gas”
  • Check Physical State of Fans
  • Check Current Draw of Fans / VSD
  • Check if time clock fitted and its functionality
  • Label Sensor with Test date Sticker
  • Provide services report
  • Provide Log / record to client


  • The System must be services twice per year – every six months
  • No Point in the car park can be more the 25 meters away from a sensor

How can We Help you?

We are CM3 Prequaified trade based company providing Mechanical services, Electrical Services, Fire and Automation (BMS)CM3 Logo

Below is a service request form, tell us about your situation and what you need. We’ll get back to you typically in a couple of hours or the next business day

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