Reference Guide
Thermotech Incorporated
2900 N. 1000 W. (801) 782-2233
Ogden, UT 84414 Fax: (801) 782-1746
www.ThermotechHeatDetectors.com

Model 302 Series Reference Guide

WARNING - failure to comply with the information in this document may result in property damage and/or serious bodily injury and will eliminate all express and implied warranties.

DESCRIPTION

A. General - The 302 series automatic heat detector is designed for fire detection with alarm systems. Thermotech detectors are normally open devices and are "rate compensation type" detectors. All four models are self-restoring, hermetically sealed, shock and corrosion resistant, nonferrous, and tamperproof.

B. Principles of Operation - The Model 302 operates on the principles of a rate compensation detector. The detector consists of a high expansion aluminum tube that encases two insulated struts with opposing open contact points. The high expansion sensing shell and the expansion struts have a different coefficient of expansion. This allows the detector to react to changes in temperature in the following two ways:

Slow Rate of Temperature Rise - A slow rate of temperature rise allows the heat to penetrate the inner expansion struts. As the temperature rises, the tubular shell and the struts both expand until the total device has been heated to the rated temperature. At this point, the silver contact points close which initiates the alarm.

Rapid Rate of Temperature Rise - When subjected to a rapid rise in temperature, there is not as much time for heat to penetrate the inner strut. The rapid lengthening of the shell along with the slower reaction of the struts allow the silver contact points to close at a lower level. The detector reacts almost instantly to the rapid increase in temperature and "compensates" for thermal lag inherent in conventional fixed temperature detectors.

When the ambient air temperature drops below the detector's rated temperature, the shell contracts which forces the contacts to open and the detector to reset itself.

C. Specific Model Descriptions - Thermotech 302 Series Models include Models 302, 302-AW, 302-ET, and 302-EPM. All models are available in either 135°F or 194°F ratings. See "Application of Specific Models" below for a description of all Thermotech 302 Series Models.

GENERAL APPLICATION

A. General - Application of Model 302 Series Automatic Heat Detectors should be based on sound engineering judgement and on industry standards as set forth by the National Fire Protection Agency in the NFPA 72, National Fire Alarm Code and/or the local authority having jurisdiction.

B. Whenever a Thermotech Heat Detector is used with an automatic fire suppression system (including, but not limited to, pre-action and deluge sprinkler systems, carbon dioxide systems, halon systems, and dry chemical systems), Thermotech requires the operation of at least two automatic detectors to initiate the alarm response. This is commonly referred to as cross-zoning and is necessary to eliminate premature discharge of the system. Refer to NFPA 72. WARNING - failure to comply with this requirement may result in property damage and/or serious bodily injury and will eliminate all express and implied warranties.

C. Maximum Ceiling Temperatures - The following chart is based partly on the NFPA 72 and can be used to determine which temperature rating should be used in any particular application:

Detector's Rated Temperature(°F)

Minimum Ambient AirTemperature (°F)

Maximum Ceiling
Temperature (°F)

135°
-40°
100° - 115°
194°
-40°
150° - 155°

Example: If a detector was being installed in a residential car garage and the maximum ceiling temperature was expected to reach 103°F two days out of the year, use a 194° rated detector. If the ceiling temperature will never reach above 100°, use 135° rated detector.

D. Temperature Fluctuation Considerations - Detectors rated at 135°F should not respond to momentary temperature fluctuations less than 30°F/minute between 60°F and 100°F. Detectors rated at 194°F should not respond to momentary temperature fluctuations less than 50°F/minute between 60°F and 150°F.

Thermotech detectors should not be used in environments with temperature fluctuations greater than the above. Do not install Thermotech detectors in hot air ducts, in front of heaters, in paint booths that use heat to cure paint, etc., etc.

E. Direct Heat Sources - The aluminum tube acts as a collector of heat when sources of heat radiate directly on the tube. Keep out of direct sunlight and away from radiating heat sources including the direct flow from heaters and heat ducts.

APPLICATION OF SPECIFIC MODELS

A. General - Application of Model 302 Series Automatic Heat Detectors should be based on sound engineering judgement and on industry standards as set forth by the National Fire Protection Agency in the NFPA 72, National Fire Alarm Code and/or the local authority having jurisdiction. Detectors are not directionally affected, detectors can be mounted horizontally or vertically.

B. Listed Spacing - Spacing is based on smooth ceilings that are up to 10' high. Refer to NFPA 72 for ceilings that are not considered smooth or are higher than 10'. RTI Classification: 135=Quick 194=V Fast.

C. Model 302 - Most basic model. For interior vertical mounting in any atmosphere that is compatible with terminal screw connections.


LISTED SPACING
MODEL
Listing 302 302-AW 302-ET 302-EPM
UL 50' X 50' 50' X 50' 50' X 50' 40' X 40'
FM 135
FM 194
20' X 20'
30' x 30'
20' X 20'
30' x 30'
20' X 20'
30' x 30'
Not Listed
Not Listed

Horizonal
mount UL

40' X 40' 40' X 40' 40' X 40' 30' X 30'


D. Model 302-AW - All-weather type detector with four wire leads. Hermetically sealed for moisture proof or dust proof installations. Vertical mounting.

E. Model 302-ET - Same as Model 302-AW except with plastic hexagonal grip bushing with 1/2inch conduit threads for attachment to threaded hub cover, tee conduit, or any outlet box. Vertical or horizontal mounting. Hand tighten only.

F. Model 302-EPM - Explosion proof detector intended for use in fire alarm systems where wiring is enclosed in threaded rigid conduit, and related fittings are listed for use in hazardous locations, division 1, Class I, Groups C and D, and Class II, Groups E, F, and G. Bushing has hexagonal grip and 1/2 inch size conduit threads for attachment to threaded hub cover of fixture fittings that are listed for use in hazardous locations. Explosion proof, vertical or hortizonal mounted. Interior use only. Hand tighten only.

G. AP-P - Decorative white plastic adapter plate for mounting Models 302 and 302-AW to any 3" outlet box or 4" octagon outlet box.

MAINTENANCE

Model 302 series heat detectors are low maintenance. Detectors automatically restore when temperatures drop below their rated temperatures. Accumulation of dust and dirt should not adversely effect detectors. If detectors must be cleaned for aesthetic purposes, turn alarm system off and clean detectors with a damp cloth.

Thermotech heat detectors are precision devices that should be handled carefully. DO NOT DROP or expose to Excessive Vibration.

TESTING
A. General - Refer to NFPA 72, National Fire Alarm Code and/or the local authority having jurisdiction to determine testing frequency, record keeping, and other testing considerations.

B. Testing Methods - The following methods can be used to test for OPERATION and SENSITIVITY by the customer:
1. OPERATION - Testing for operation is simple and can be done before or after the detector has been installed. Heat the detector with a common hair dryer. Do not use any device with an open flame to test detectors. Detectors should operate shortly after the hot air is applied.

2. SENSITIVITY - Testing for sensitivity is more difficult and requires a laboratory oven where the temperature can be controlled and where calibrated measuring devices are used. Maintain a temperature of 20° F below the detectors' rating for 5 minutes and then increase at a rate of 1 °F/min. Each sample must be connected to a power source (6 V) and a signaling means for proper indication of operation. The air is to be constantly circulating during the test. Under these conditions, accurate data can be obtained.



WARRANTY

Thermotech warranties model 302 series heat detectors for up to one year for any defects in material or workmanship. This warranty is limited to proper maintenance, testing and installation as set forth herein, by the National Fire Protection Agency, National Fire Alarm Code, and/or the local authority having jurisdiction.

It is the purchaser's responsibility to test and determine the suitability of the detector for the purchaser's intended use, and purchaser assumes all risk and liability whatsoever reguarding such suitability.  In no event will Thermotech be obligated to pay damages to purchaser in any amount exceeding the price that the purchaser paid for the detector.  Installation costs are the sole responsibility of the purchaser.


Special Considerations

Temp. Rating °F
Max Ceiling Temp. °F
Min. Ambient Air
135 115

-40°F

194 155



Electrical Rating

Voltage Current
6-125 VAC 5 amps
6-25 VDC 1 amp
125 VDC 0.5 amp