Fire damper

• US 4,084,744 A
• Filed: 05/05/1976
• Issued: 04/18/1978
• Est. Priority Date: 05/05/1976
• Status: Expired due to Term

• Current Assignee: Jr.; Charles Edwin Wilson
• Original Assignee: Jr.; Charles Edwin Wilson
• Inventors: Wilson, Charles Edwin Jr.
• Primary Examiner(s): Wayner, William E.
• Assistant Examiner(s): Jones, Larry
• Application Number:
  US05/683,494
• Time in Patent Office: 713 Days
• Field of Search: 98/1, 98/86, 236/49, 49/2, 49/31, 169/48, 169/49, 251/67, 251/68, 251/69, 251/72, 251/74, 137/457, 137/468, 110/163, 126/285.5, 126/285 R, 55/104, 55/106, 55/217, 55/274, 55/270, 55/418
• US Class Current: 236/49.2
• CPC Class Codes: A62C 2/12 Hinged dampers
• CPC Class Codes: A62C 2/247 electric
• CPC Class Codes: F24F 11/35 by closing air passages
• CPC Class Codes: F24F 13/0236 with ducts including air distributors, e.g. air collecting boxes with at least three openings
• CPC Class Codes: F24F 13/1426 characterised by actuating means

Abstract

The fire damper of this invention is to protect sensitive areas and equipment from fires which originate in the process of a plant. The invention, for example, may have utility in the protection of bag house filters and the like. It will, however, by way of example only, be largely described herein as applied to an electrostatic air cleaner located on a process stack. In recent years such electronic air cleaners, often in the form of a two-stage electrostatic precipitator, have become quite popular. Such apparatus, however, is quite sensitive to high temperatures such as are occasioned by fires and may readily be destroyed when exposed to them. In this invention a temperature rise is sensed by means of electrical detectors and relayed to the control box of the fire damper. Here it is translated into a control signal which actuates mechanism which will withdraw a latch means which supports a vent door whereafter such door falls by means of gravity to block the duct leading to the air cleaner while at the same time venting the plant process air and fire to outside atmosphere. The mechanism which actuates the latch means such as by pulling a steel shaft or pin may be either electrical or pneumatic. A satisfactory electrical mechanism is an electric solenoid that moves the latch or pin release. A satisfactory pneumatic release is one which operates by means of a pressurized gas, preferably a dry and inert gas like nitrogen where there is no risk of freezing or flamability, to operate a pneumatic cylinder-piston arrangement to withdraw the pin which supports the vent door. The vent door is so located and pivoted that, when the latch pin is pulled, it will immediately swiftly move into fire damping position by means of gravity. Fire and heat are then simultaneously vented vertically to atmosphere through that opening in the fire damper thus uncovered by the door in moving to its fire damping position, by virtue of which any possible flashback into the process, due to the failure of a relief damper or the like to open when the duct fire damper door is closed, is prevented.

Claims

1. A fire damper comprising a housing having a first side open to receive gases from a first area, a second side normally open to permit said gases to flow to a second area, and a third side normally closed;

a door pivotally connected to said housing in a first position so as normally to effect the closing of said third side while said first and said second sides are open, said door being swingable by gravity to a second position in which said normally open second side is closed by said door and in which said normally closed third side is open so as to permit said gases to flow from said housing through said third side only;

releasable latch means to normally maintain said door in said first position; and

heat sensitive means to actuate said releasable latch means in response to temperature changes in said first area whereby to permit said door to swing from said first position to said second position, said heat sensitive means including pneumatic means to actuate said latch means, and a heat sensor in the region of said first area, said heat sensor being electrically connected to said pneumatic means, whereby said releasable latch means are actuated in response to a temperature increase in said first area.

2. A fire damper comprising a housing having a first side open to receive gases from a first area, a second side normally open to permit said gases to flow to a second area, and a third side normally closed;

a door pivotally connected to said housing in a first position so as normally to effect the closing of said third side while said first and said second sides are open, said door being swingable by gravity to a second position in which said normally open second side is closed by said door and in which said normally closed third side is open so as to permit said gases to flow from said housing through said third side only;

releasable latch means to normally maintain said door in said first position; and

heat sensitive means to actuate said releasable latch means in response to temperature changes in said first area whereby to permit said door to swing from said first position to said second position;

said heat sensitive means including an electric solenoid to actuate said latch means, and a heat sensor in the region of said first area, said heat sensor being electrically connected to said electric solenoid, whereby said releasable latch means are actuated in response to a temperature increase in said first area.

3. A fire damper adapted to be placed in duct work for normally leading air from a first area to a second area of a building and the like, which fire damper comprises:

a main housing;

a door pivoted in said main housing, said door having a first position in which one side of said housing is open to said first and second areas while an other side of said housing is closed;

latch means to hold said door in said first position; and

heat sensitive means to actuate said latch means in response to temperature changes in said first area so that said door moves by gravity from said first position to a second position in which said one side of said housing is closed and said other side of said housing is opened;

said latch means comprising a latch member on said door, a latch plate on said main housing, aligned orifices in said latch member and said latch plate when said door is in its said first position, and a pin extending through said orifices to hold said door in said first position until such time as said latch means is actuated whereby said pin is withdrawn from said orifices and said door moves by gravity from said first position to said second position;

whereby when said first damper is in said duct work and said one side is in communication with both said first and second areas, actuation of said door to said second position will cut off flow of air to said second area and open said fire damper to flow of air from said first area and out of said fire damper.

4. The fire damper of claim 3 including a pneumatic piston-cylinder means, said pin being connected to said piston-cylinder means, a source of pressurized fluid for said piston-cylinder means, said piston-cylinder means normally maintaing said pin in said alligned orifices, the said means to actuate said latch means including a control device for permitting pressurized fluid to enter said piston-cylinder means and actuate same to withdraw said pin from said orifices.

5. The fire damper of claim 4 in which said fluid is nitrogen.