T4 is Crowcon’s personal protection solution for detecting the four most common gas hazards:

  • Carbon Monoxide (CO)
  • Hydrogen Sulphide (H2S)
  • Flammable Gases 
  • Oxygen Depletion (O2)

Offering you compliance, robustness and low cost of ownership in a simple to use solution. The large single button and intuitive menu system allows T4 to be operated wearing gloves with minimal training.

Crowcon’s toughest portable yet, T4 is durable by design and includes an integrated rubber boot as standard. An optional clip-on filter cover, which is easily removed and replaced, ensures sensors are protected in the dirtiest environments. Drop tested to 4m and well protected from water ingress through IP65 and IP67 certification, T4 allows uninterrupted working in the most demanding environments.

Now with improved detection of pentane, hexane and other long chain hydrocarbons.

T4 contains a wide range of powerful features to make everyday use easier and safer:

TWA Resume

Unique to T4, the TWA Resume function ensures toxic gas exposure is calculated accurately over an entire shift, even if T4 is switched off for a break or during travel to another site.

When most portable detectors are turned off, the algorithm that assesses TWA exposure assumes that it’s the end of the shift. When turned on again, these detectors act as if it is a new work shift, ignoring all previous measurements. The TWA Resume function however, provides the option to include previous measurements from within the correct time frame.

18 hour battery

With a battery life of 18 hours, T4 allows multiple or longer shifts to be worked between recharging.

Positive Safety

Crowcon’s visual ‘traffic light’ indication, provides constant visual assurance that T4 is operating soundly and conforms to site bump test & calibration policy. The bright green and red Positive Safety LEDs are visible to all and offer a quick, simple and comprehensive indication of monitor status to both the user and others around them.


Size W135 x H80 x D35 mm (5.3 x 3.1 x 1.4in)
Weight 282g (9.9oz)
Durability Drop tested to 4m onto concrete
Alarms Audible >95dB
Bright red/blue visual LEDs
Integrated vibrating alert
Display Front mounted, backlit. Optional 180° flip for easy viewing whilst worn
Logging 130 hours of data logging; Up to 3500 events
Battery Rechargeable Li-ion
18 hour typical runtime
5.5 hour recharge
Operating temperature -20°C to +55°C (-4°F to +131°F)*
Humidity 10 to 95% RH @ 40°C non-condensing
Ingress protection Independently tested to IP65 and IP67
Approvals ATEX and UKCA: II 2 G Ex db ia IIC T4 Gb Tamb -20°C to +55°C (T4 Type 2)

IECEx: Ex db ia IIC T4 Gb -20°C ≤ Ta ≤ +55°C (T4 Type 2)

UL and cUL: Use in hazardous locations Class 1 Div 1 groups A,B,C,D only as to intrinsic safety

INMETRO: Ex db ia IIC T4 Gb -20 °C ≤ Ta ≤ +55 °C

MED: Directive 2014/90/EU

Standards EMC Directive 2014/30/EU
Interface USB communications lead
Accessories Included with T4:

Integrated alligator clip and tethering loop

Bump/Calibration plate

Available separately:
Single unit cradle charger, 10 unit cradle charger; Vehicle charger
Clip on filter plate for sensor protection in dusty environments
I-Test automated bump and calibration station

Crowcon Connect Compatible? Yes

* Toxic and oxygen sensors are not rated for continuous operation above 50°C (122°F)

Gases and Ranges

Gas Range Resolution
Oxygen (O2)  0-30% Vol.  0.1% Vol.
Flammable  0-100% LEL  1% LEL
Hydrogen sulphide (H2S)  0-100ppm  1ppm
Carbon monoxide (CO) 0-1000ppm  1ppm


Below is a small selection of the accessories available for the T4.

Bump/Calibration plate


For applying test gas to T4

External filter plate


Clip-on filter for additional protection in dusty environments. Protects the sensors from contamination.



Easy automated bump testing and calibration solution.

Cradle charger


Docking station for easy charging. Includes multi region power supply.

10 way charger


Charge and store up to 10 units. Requires only a single power outlet.
*Not available for UL certified products.

Vehicle charger


Charge and store securely during transit.

*NEW* Portables Pro software


Newer version – clean, easy and intuitive to use.
Service edition makes servicing T4 very easy.
Visit software downloads to download.

USB communications lead


For PC connection to T4





Power and Communication Cables


Basic Operation:


Includes: Switching T4 on, sensor zero and TWA Resume functions. Duration: 1m:37secs

Watch video

  Home screen

Includes: T4 gas level display home screen. Duration: 18secs

Watch video


Includes: Switching T4 off. Duration: 22secs

Watch video


Includes: Using the T4 cradle charger, 10 way charger and vehicle charger. Duration: 45secs

Watch video


Includes: Activating the display backlight. Duration: 19secs

Watch video

Advanced Features:

  Quick view

Includes: View status information without switching T4 on. Duration: 1m:02secs

Watch video

  Information screen

Includes: View status information during operation. Duration: 1m:01secs

Watch video


Includes: View average gas exposure measurements. Duration: 37secs

Watch video


Includes: View average gas exposure measurements. Duration: 40secs

Watch video

  Peak mode

Includes: Switch display to peak level readings. Duration: 57secs

Watch video

  Manual zeroing

Includes: Perform a sensor zero when in clean air. Duration: 31secs

Watch video

  Gas sampling

Includes: Using the T4 aspirator plate and hand bulb to sample gas. Duration: 1min19secs

Watch video

Bump Testing:

  Manual bump

Includes: Bump test T4 using the clip-on bump/calibration plate. Duration: 1m:10secs

Watch video

  I-test bump

Includes: Bump test T4 using the automated I-Test bump and calibration station. Duration: 1m:12secs

Watch video

Additional Information:

T4 user manuals and datasheets can be found in our downloads