The Sewerin EX-TEC OD 4 is the ideal tool for measuring mercaptan concentrations in natural gas.  With proper care and regular maintenance, you can expect accurate measurements for a long time to come.

As an addendum to the EX-TEC OD 4 Operating Manual, Sewerin recommends that before any field use of the EX-TEC OD 4, it must be calibrate (or bump tested) with a known concentration of Mercaptan, Figure 1.  This is recommended on the same day before a sampling of natural gas is taken when you conduct your field work.  By doing so, the electrochemical sensor that detects the concentration of Mercaptan (TBM) becomes ‘sensitized’ to the presence of a known concentration of Mercaptan.  When using your calibration gas, it is essential to ensure that there are no connecting pieces made of rubber or synthetic substances between the EX-TECX OD 4 and the connection to the gas main unless these consist of inert materials (e.g. Viton or nylon).

A further factor that affects the measurement of sulphur compounds with the EX-TEC OD 4 is the flow rate through the measurement chamber, which must always exceed 20 l/h.

Cameron Instruments sources our Mercaptan Calibration Gas and accessories through Linde, but they could be sourced from any Specialized Gas Supplier.  Figure 2 (Linde) lists the test gas information used in-house for the purposes of bump testing.

Please note that on all new orders of the Sewerin OD4, Cameron Instruments will provide an initial bump test with Mercaptan before the OD4 is shipped to our customer.  Once the EX-TEC OD 4 has been bump tested with the Mercaptan Calibration Gas, you can be assured of accurate readings when field work is carried out.  Your Mercaptan sensor will require replacement/servicing every 9-12 months for optimal performance, and this work can be completed by Cameron Instruments in our Guelph, ON lab.

For further information, please contact our Calibration Lab at:  1.888.863.8010 or


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