1. Where can I find my serial number?

If you have an instrument in our GFM range the serial number will be on the back of the instrument at the top, this will be a 4-5 digit number.

If your instrument is an LMSXi the serial number will be on the base of the instrument, this will be a 4 digit number.

If you have a GF60 the serial number will be located on the back of the instrument at the bottom.

Please note you can also find the serial number on any of these types of instrument by turning them on, the serial number will appear on the screen. Other instruments such as the LMSp will only show the serial number when the screen is on.

2. What is the cost of a service/recalibration?

The cost of a service/recalibration is different for each type of instrument. If you require a price, then call us on +44 (0) 2476 303 311 and ask for our service department, where you will get a price upon request. You can also request a written quotation which will be sent through to your email the same day.

The service/recalibration cost covers the replacement of the O2 cell within the instrument (excluding GFM1xx series). Within the quotation we will also advise of any components to be replaced due to their age.

3. What is the turn around of the service/recalibration for my instrument?

The length of time for a service/recalibration of your instrument will depend on what type of instrument you have. The table below shows the average turn-around times. Please note that turn-around time may increase if we find any major faults with your instrument.

Type of instrument

Usual turn around

GFM 100 series 1 week
GFM 200 series 1 week
GFM 400 series 2 weeks
GFM 600 series 1 week
LMSXi & LMSx 1 week
LMSp 2 weeks
PCO2 1 week

If you have not received your instrument back on time you can call our service department who will be able to give you an accurate date when it will be despatched or tell you the whereabouts of your instrument using our couriers’ tracking number.

4. How often should my instrument be serviced?

We advise that Instruments are  returned every 12 months so that they can be serviced / maintained for optimum operational use.

5. What is performed during a service/recalibration?

Please refer to our servicing page for a full description of the work carried out during the service/recalibration of your instrument.

6. How do I perform a user calibration?

Full details of this are located in the manual. We also supply known gases for user calibration.

7. How do I perform a Key3 reset on my LMSXi?

If you are having a ”memory corrupt” error with your LMSXi a key3 reset should solve your problem.
1. Switch off instrument with on/off button
2. Press and hold key 3 depressed whilst the instrument is switched on
3. Keep key 3 depressed
4. Wait for message on screen ‘Press confirm to delete all stored readings’
5. Now release key 3 quickly
6. Press OK
7. Instrument display will read ‘initialised’ and will switch off
8. Wait for instrument to switch back on automatically
9. If this does not happen after 60 seconds, press RED reset button/LED & repeat steps 1 to 8

This operation may sometimes not work first time. Keep trying until the ‘Press confirm to
delete all stored readings’ and the ‘initialised’ message have been clearly seen at the right

8. Why is my instrument not turning on?

How often do you charge your instrument?

We advise the instrument is recharged weekly to avoid the battery entering into a deep discharge. If you are experiencing this problem with your instrument we would advise leaving the instrument on charge for at least 12 hours. If this is not successful the instrument will have to be returned to Gas Data so a full repair inspection can be carried out.

9. Why does my GFM400 series instrument show negative readings?

The GFM400 series are MCERTS accredited instruments. One of the requirements of this certification is that the instrument has “live zeros”. This is to allow the user to track any drift in the instruments or sensors.

For example, if the H2S reading shows –10ppm in air, and then when used to measure a sample it reads 1500ppm, the true reading is 1510ppm. If the H2S reading shows +10ppm in air, and then when used to measure a sample it reads 1500ppm the true reading is 1490ppm.

GFM400 instruments also display LEL. This is a calculated value – one of the values used in the calculation is the CH4 level. Due to the “live zero” the CH4 reading can become negative. This causes the LEL calculation to be invalid, and results in the instrument displaying chevrons (<<<<) for the LEL calculation. This is normal and expected.

In most cases the “live zero” results in a very small error. For example if the instrument is fitted with a H2S cell which has been calibrated to show 0-2000ppm, an error of -10ppm represents only a 0.5% full calibration scale, which is well within the tolerance specified on the calibration certificate and is acceptable.

10. What does it mean when my instrument is showing chevrons pointing to the right?

If you see this on your instrument (>>>>) it means that the concentration of the gas you are sampling is higher than the maximum range calibrated on your instrument.

11. Does Gas Data sell bottled test gas?

Yes Gas Data do sell a range of test gases in relation to the applications that we are involved in.

If you would  like further information about which bottled test gas we can provide please phone +44 (0) 2476 303 311 or email enquiries@gasdata.co.uk.