ignition interlock facilities
Commercial and Industrial Air handling units
Canada Blower Co. has many different types of industrial Make-Up Air Systems developed for the larger industrial plants ventilation. An improvement of the industrial plants on the environment can have significant benefits in terms of increased production, less errors and a decrease in complaints and absenteeism among employees.
Air Handling Units for the Make-Up Air and Space Pressurization applications have the following characteristics:
- Outlet temperature is usually monitored with a probe mounted near the outlet of the unit.
- Discharge air temperature is set at the control panel or using a remote station.
- Gas input is € â € œmodulatedâ using a butterfly valve, actuator and controller.
Applications for space, a room thermostat is used for outlet temperature. On a call for heat, the unit providing air heated to the maximum allowable temperature until the room thermostat is satisfied. Once satisfied, the unit will either turn off or will continue at a reduced temperature exhaust.
An option may also override be delivered. In this case, a room thermostat is supplied in addition to the basic system. The unit is set to full-fire at room temperature is too low.
Direct Units are supplied with a spark ignition transformer for the igniter.
Pilot units are supplied with an automatic pilot operated solenoid valve and a small pressure regulator â € "about 20,000 BTU â €" and an ignition transformer for the electric pilot igniter.
Pre-treatment of the system (by starting the blower for a certain time to a minimum air volume change provided) for ignition of the main burner is not required by ANSI code, but is often determined by the user. This should be provided when a building containing combustible dust or fumes which may achieve and collect in a gas-fired unit while not active.
To ensure safe operation of a gas fired heating, a number of security are usually provided:
A. Damper Limit Switch â € "Dampers should be completely open to unit will operate.
B. Air Proving Switch â € "Located near outlet unit to demonstrate airflow before igniting burner.
C. Flame Monitoring â € "discussed above. Closed unit on flame failure.
D. High Temperature Limit â € "Signals unit to reduce gas when the maximum allowable temperature is reached. If the air temperature limit, the switches off.
E. High Gas Pressure Switch â € "Closed unit to protect against spikes in the inlet gas pressure regulator.
F. low gas pressure switch â € "This closes unit at low pressure at the inlet detected. Redundant safety device, because small flash unit would be closed.
G. Safety valve â € "Responding to various inputs above â €" exit gas.
Return Air Units are widely used for direct heating applications in the fire area. They can be supplied with a maximum 80% return/20% fresh air, per ANSI standards. Other options include a 50/50 arrangement. â € € œ80/20â units are configured to modulate the return/20% 80% to 100% outside fresh air or fresh air. 50/50 units are generally designed to switch from 50% yield / 50% fresh and 100% fresh, with no differentiation.
All return air must be placed in the downstream of the burner and not by recirculation of the burner. This is to prevent the accumulation of waste combustion process within the building. It also prevents contaminants originating in the built environment to be transmitted through direct fire burners. The burning of unknown contaminants can be a serious safety or Indoor Air Quality problem, and should be avoided.
Additional information is available at the Canada Blower company web site http://www.canadablower.com/ahu/index.html.
Susan Terlitski
Air Handling Systems Engineering
Canada Blower
http://www.canadablower.com/index.html
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