BY GEORGE LANTHIER
Figure 5
By exhaling slightly into the instrument, a positive pressure should register and then the instrument should return to zero. By twirling hose end or by inhaling across tube, a negative pressure should register and then the instrument should return to zero. If it does not return to zero after a couple of samples, the instrument is most likely defective.
Checking the wet-type draft gauge, Figure 5, check to be sure that gauge is level and zeroed.
Figure 6
Check out the same as the dry-type gauge. However, if this instrument does not return to zero after a couple of samples, thoroughly clean the instrument and recharge with clean gauge oil.
It has also been found that when draft gauges respond slowly or are sluggish, the following components should be checked:
• leads and probes may be plugged or leaking.
• pointer may be touching scale.
• shut-off rings on wet-type are leaking air.
Checking the smoke tester, Figure 6, insert clean test paper into instrument.
Block off end of sampling tube. Pull plunger handle about 1 inch and release. Handle should return to about the original position. If no resistance is met or if instrument does not return to original position, the instrument should be checked for leakage. An atmospheric test should be made of the instrument. If, after ten full strokes, a smoke reading is observed which can be measured on the chart, another test with a clean test paper should be performed.
If after this, the instrument still measures smoke, the instrument should be disassembled and cleaned. Be sure to lubricate the plunger-type cylinder with the proper material after servicing. NOTE: White petroleum jelly, aka Vaseline ® is acceptable.
Checking the CO2 analyzer, Figure 7,
20 FEBRUARY 2026 | FUEL OIL NEWS | www. fueloilnews. com