Product Overview

FANs 121, 125
Temperature Controls Section A
Product Bulletin A19AUC, A19BUC
Issue Date 1091
© 1991 Johnson Controls, Inc. 1
Code No. LIT-121035
Part No. 3544, Rev. I
Types A19AUC, A19BUC Fixed Differential
Thermostat For Hazardous Location
Application
The A19AUC and A19BUC
thermostats are designed for
use in locations where
flammable and explosive
mixtures of vapors and gases
with air or combustible dust in air
are present. Listed at UL for
“Hazardous Locations, Class I,
Group D (NEMA 7) and Class II,
Groups E, F and G (NEMA 9)”
as defined in the National
Electrical Code. The SPDT
contact unit provides open high
or close high action for either
heating or cooling applications.
The thermostats are available to
cover sensed temperatures from
-30 to 475°F (-34 to 246°C).
Closed tank fittings and bulb
wells are available for immersion
applications.
All Series A19 thermostats are
designed for use only as
operating controls. Where an
operating control failure
would result in personal injury
and/or loss of property, it is
the responsibility of the
installer to add devices
(safety, limit controls) or
systems (alarm, supervisory
systems) that protect against,
or warn of, control failure.
Features
• Dependable and precise
snap-acting contacts
enclosed in a dust protected
case and the liquid filled
sensing element are field
proven.
• Unaffected by barometric
pressure and cross ambient
temperature problems for
“repeat” accuracy.
• SPDT contacts for use on
either heating or cooling
applications.
• UL Listed, CSA Certified for
“Hazardous Locations.”
General Description
The temperature sensing
elements are liquid filled,
providing uniform differential
throughout the selected
adjustment range. Remote bulb
elements are regularly supplied
with a 6 foot. (1.8 m) capillary.
Requests for other construction
variations should be sent to
Customer Service.
The range adjustment changes
the cut-in and cutout points
alike. The differential is
nonadjustable.
Fig. 1 -- A19BUC thermostat
with air bulb.
Fig. 2 -- Interior view of the
A19AUC with clamp on bulb.
These thermostats are suitable
for installation in hazardous
locations as defined in the
National Electrical Code, where
the atmosphere may contain the
following:
1. Certain vapors and gases.
2. Dust such as aluminum,
magnesium or their
commercial alloys.
3. Carbon black, coal or coke
dusts.
4. Flour, starch or grain dusts.
Specifications