Technical data

Natural Gas (G20 I

) Tubular Heater

The minimum allowable pre-purge time requires calculating [BS EN1020:1998 clause 6.38].

To do this only the Carbon Dioxide CO

figure needs to be measured.

E.G. on a model 170 the calculated minimum time is = 354.8 / ((100 / CO2) + 1)

If the measured CO

is 6.7%

Then 100 / 6.7 = 14.9

14.9 + 1 = 15.9

Therefore minimum pre-purge time is = 354.8 / 15.9 = 22.3 seconds

The calculation to be conducted is given below for all models:

Model 40 Minimum pre-purge time = 628.8 / ((100 / CO2) + 1)

Model 70 Minimum pre-purge time = 475.4 / ((100 / CO2) + 1)

Model 100 Minimum pre-purge time = 398.0 / ((100 / CO2) + 1)

Model 135 Minimum pre-purge time = 366.8 / ((100 / CO2) + 1)

Model 170 Minimum pre-purge time = 354.8 / ((100 / CO2) + 1)

Model 200 Minimum pre-purge time = 347.4 / ((100 / CO2) + 1)

Model 250 Minimum pre-purge time = 286.2 / ((100 / CO2) + 1)

Model 330 Minimum pre-purge time = 269.7 / ((100 / CO2) + 1)

Model 410 Minimum pre-purge time = 261.4 / ((100 / CO2) + 1)

Model 490 Minimum pre-purge time = 269.2 / ((100 / CO2) + 1)

The pre-purge time must then be measured. If the measured pre-purge time is lower

than the calculated time STOP and contact Benson Heating.