Flach & Le-Roy Ltd

Main Air Duct Pressure Gauge


Your main air duct, designed, manufactured and supplied by us is equipped with a gas test gauge (water manometer) model 257C. Its purpose is to provide you with a fast and easy method for checking that your fans, duct outlets and height of your stack are set up to the most efficient configuration for efficient drying and conditioning of your crop/woodchip.

For a 10-foot stack your target airflow is 24 ft/min through the crop. At this airflow, depending on the number of duct outlets that you have open, your test gauge should be reading approximately 4' WG pressure. For a 12-foot stack the pressure will be nearer 6' WG and the flow rate approximately 20 ft/min through the crop. Any wide variations from these parameters should be investigated and corrected. Typical problems range from stack height, top layer compaction to calculating the number of outlets to be opened and fan installation issues. Contact us on the number below if you have any problems relating to these instructions.

On completion of the main air duct your gauge will be fitted in the most convenient position for you to check it regularly when the fans are running. On initial fitment and at routine checks the gauge is filled with tap water to about the zero level in the cursor window. The cursor and scale is then adjusted so that the water level is opposite the twin cursor points. The gauge is now set and ready for use. Remember to check it regularly to adjust the water level to allow for evaporation.

It is unlikely that you will encounter any snags with the test gauge but blockages sometimes occur so check that the water level is at the same level on either side of the U-tube and investigate any discrepancies. You can test the gauge for leaks by removing the gauge from the duct and blowing gently on one side of the gauge so that the water columns are at different heights on either side of the scale. Block off the other of the U-tube with a finger and wait 5 minutes. If there is any change in height of the water, replace the gauge.

Care and Maintenance: from time to time remove the water from the U tube using liquid soap and warm water to prevent discoloration inside the U tube. If the discoloration becomes intolerable, disassemble the gauge completely using a suitable screwdriver to remove the screws and wash the plastic U tube out as above. The spring at the base of the U tube is stainless if it becomes dislodged or out of position, replace so that the spring is exactly at the base of the bend. Reassemble.

Customer reviews

No reviews were found for Main Air Duct Pressure Gauge. Be the first to review!