cashco 135 Installation, Operation & Maintenance Manual

Low temperature shutoff

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I. DESCRIPTION AND SCOPE

The Model 135 thermal probe is a low temperature shutoff device with an integral, rigid insertion bulb used to protect

downstream piping systems and equipment from experiencing temperature excursions below desired minimum

operating temperature due to equipment malfunction or customer overdraw of system capacity.

The Model 135 thermal probe is not a stand-alone device. It is primarily used with a pressure loaded reducing regulator

with fail-close action upon loss of loading pressure. Used with any compatible fluid that can be vented to atmosphere

in an environmentally acceptable method. This combination of equipment is known as a PRESSURE/LOW

TEMPERATURE CONTROL MODULE (PTCM). It typically consists of a Model 135 thermal probe, an unloading

backpressure valve, flow restricting orifices and a main regulator, such as the Model DA4. Refer to Section II of this

IOM for PTCM principles of operation and SECTION III for system installation.

II. PRINCIPLES OF OPERATION

1. As the Model 135 thermal probe (5) external

sheath is exposed to lower temperatures, it con-

tracts in length. The internal Invar rod remains

unchanged in length, pushing a ball/plug away

from its seat, allowing the inlet gas pressure to be

"vented".

2. The PTCM low temperature protection is provided

through the Model 135 thermal probe (5). When

III. INSTALLATION

1. Insert the Model 135 thermal probe (5) in the

upstream pipeline requiring control. Seal the 1/2"

(DN15) NPT threads with process compatible

thread sealant and turn clockwise (CW) until tight.

PTCM Start-up:

a. The Model 135 thermal probe (5) temperature

is factory calibrated per customer's order speci-

fications.

INSTALLATION, OPERATION & MAINTENANCE MANUAL (IOM)

MODEL 135

LOW TEMPERATURE SHUTOFF

SECTION I

SECTION II

SECTION III

the fluid is approximately 8° F (4.5° C) above the

setpoint, the Model 135 thermal probe (5) will

begin to open, lowering the loading pressure and

thereby the delivery pressures. The delivery flow

rate is reduced by this action. When the fluid is at

the setpoint, the Model 135 thermal probe will

reduce the loading pressure to 5 psig (.34 Barg),

essentially closing the main regulator (7). When

the fluid is slightly below setpoint the main regula-

tor (7) will close tight.

b. Isolation block valves (9,10) are open and the

bypass valve (8) should be closed. Upon

start-up, the PTCM becomes pressurized from

the storage tank as normal operating pres-

sure is obtained.

c. For PTCM with Unloading Backpressure Valve

see Figure 2. The delivery pressure is set by

the adjusting screw on the backpressure un-

loading valve (1). Adjust the loading pressure

until the gauge (6) reads nominally 6 psig (.41

Barg) higher than the customer specified de-

livery pressure.

IOM-135

06-02

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Summary of Contents for cashco 135

Page 1 SECTION I I. DESCRIPTION AND SCOPE The Model 135 thermal probe is a low temperature shutoff device with an integral, rigid insertion bulb used to protect downstream piping systems and equipment from experiencing temperature excursions below desired minimum operating temperature due to equipment malfunction or customer overdraw of system capacity.
Page 2 (10). The by-pass valve (8) can then be reopened to supply customer with process gas while the 1. The Model 135 thermal probe (5) is shipped from Model 135 thermal probe (5) is removed and the factory preset per the customer's order speci- replaced.
Page 3 SECTION V V. CALIBRATION 1. The Model 135 thermal probe (5) should be calibrated at the factory. SECTION VI VI. TROUBLE SHOOTING GUIDE 1. No/Low Flow or Pressure at Normal Operating Temperatures. Remedies Possible Causes A. No supply pressure to PTCM.
Page 4 Pressure Gauge Optional Gauge Stabilizer Pressure Reducing Valve Setpoint Backpressure Valve Needle Valve Typical KM pressure loaded reducing Vent to a Safe regulator used with Model 135 Thermal Location Probe. External Sensing if required. Vent to a Safe Location DA4, DAP* Figure 3: PTCM System with Cashco, Inc.