AD25 GB Issue 03
8
8 Guidelines for brooder / intensive care unit humidity
levels
8.1 Relative humidity of between 45 and 55% RH is adequate for brooding chicks and will also serve to help
counteract dehydration in an intensive care scenario. Avoid very high levels as condensation may form on
cooler surfaces.
9 Routine Maintenance
9.1 Changing the pump tube:-
The peristaltic pump will need to have its tube replaced about every 3 months. Cut a length of tube to
about 140mm. Remove the connectors and pull off the old tube. Replace with the new tube, avoiding
twists. Use the diagram on the product label to thread the tube exactly as shown over the pump head. The
tension must be sufficient to ensure complete occlusion of the tube without unnecessary flattening
between the pump rollers. Adjust tube length as necessary. Ensure that the tube does not stick together if
left for long periods by unhooking it during storage.
9.2 Changing the evaporation block:-
Change the block as necessary to maintain good evaporating efficiency. Change the block regularly to
avoid bacterial contamination.
9.3 No lubrication or further servicing is required beyond the instructions above.
10 Troubleshooting
The control system may be set to control between 20 and 80% RH. In practice the minimum and maximum
levels of humidity achievable depend upon several factors, particularly the fresh air ventilation rate. You may
need to allow 24 hours for humidity to stabilise after making changes.
If you cannot get the level of RH you want, consider these notes:
10.1 Humidity will not go low enough:-
First increase the fresh air ventilation level. This will help to dilute the moisture given up by the eggs or
animals. There will still remain a lower limit determined by the moisture content of the ambient air,
particularly in warm humid conditions. This can only be countered by dehumidification of the room air
outside the incubator with proprietary dehumidifier but is rarely a problem in practice except with ratites.
10.2 Humidity will not go high enough:-
Restrict fresh air ventilation to the minimum safe level. Remember even embryos need to breathe!
Check that water is reaching the evaporation block when the pump runs – if not check the whole length of
the tubing for kinks and check that the tubing around the pump has not become permanently flattened. If
it has, replace the pump tube. Silicone tubing is very flexible but can be damaged by sharp finger nails. A
tiny perforation on the suction side of the pump will let in air and prevent the pump drawing water.
