Apparatus and method for ventilation of animal enclosures

A ventilation control system for an animal enclosure of the differential-pressure forced-ventilation type comprising:

• a plurality of enclosure walls substantially closed except for a plurality of inlet apertures therein for the ingress of ventilating air and a plurality of exhaust apertures therein for the egress of ventilating air,
• an electrically driven exhaust fan at each said exhaust aperture,
• a plurality of electrical thermostats set to operate at respective selectable temperatures within a range of temperatures through which said enclosure is expected to operate and each controlling at least one said exhaust fan.
• closure means for each said inlet aperture variably positionable with respect thereto so as to control the effective size thereof,
• means for comparing the barometric pressure within said enclosure with that outside said enclosure,
• electromechanical drive means responsive to the output of said pressure-comparing means and mechanically connected to said closure means to move the latter in the aperture-opening direction in response to a sensed pressure differential in excess of a preselected amplitude and to move such closure means in the aperture-closing direction in response to a sensed pressure differential less than a preselected amplitude, and
• means responsive to the actuation of that one of said thermostats which is set to be operated at the highest selected temperature in said operating temperature range to operate said electromechanical drive means in the aperture-opening direction irrespective of the nature of the output of said pressure-comparing means.

In an animal enclosure of the diffential-pressure forced-ventilation type, a ventilation control system, comprising:

• means for sensing the temperature within the enclosure,
• means for exhausting air from such an enclosure at respectively different rates of flow for each of a plurality of predetermined temperatures, the rate of exhaust flow being greater for each successively higher temperature,
• means for admitting air into such enclosure at a rate of flow selectable over a range from a minimum to a maximum flow,
• means for controlling said admitting means to maintain a first predetermined difference between the barometric pressure within such enclosure and that outside such enclosure, and
• means for disabling said controlling means at the highest of said predetermined temperatures and for setting said admitting means for maximum flow, thereby establishing a second predetermined difference between the barometric pressure within such enclosure and that outside such enclosure.

The method of automatically maintaining the barometric pressure within an animal enclosure at either of two predetermined amplitudes relative to that outside such enclosure, comprising the steps of

• exhausting air from such enclosure at respectively different rates of flow for each of a plurality of predetermined temperatures, the rate of exhaust flow being greater for each successively higher temperature,
• admitting air into such enclosure at a rate of flow selectable over a range from a minimum to a maximum flow,
• normally controlling said admission of air to maintain a first predetermined difference between the barometric pressure within such enclosure and that outside such enclosure, and
• ceasing such normal differential-pressure control at the highest of of said predetrmined temperatures and admitting air at the rate of said maximum flow, thereby establishing a second predetermined difference between the barometric pressure within such enclosure and that outside such enclosure.