Dial thermometer

Thermocouples tend to be rehable, but dial thermometers may need to be puUed and verified for accuracy. 

RECIRCULATION FROM PUMP DISCHARGE THROUGH A ROW CONTROL ORIFICE (WHEN NECESSARY) AND A COOLER AND INTO THE SEAL CHAMBER, ( DIAL THERMOMETER (g) IS OPTIONAL)... 

RECIRCULATION IS FROM A PUMPING RING IN THE SEAL CHAMBER THROUGH A COOLER AND BACK TO THE SEAL CHAMBER. THIS PLAN CAN BE USED ON HOT APPUCATIONS TO MINIMIZE HUT LOAD ON THE COOLER BY COOLING ONLY THE SMALL AMOUNT OF UQUID THAT IS RECIRCULATED. ( DIAL THERMOMETER IS OPTIONAL)... 

FLUID IS INJECTED INTO THE SEAL CHAMBER FROM AN EXTERNAL SOURCE. CARE MUST BE EXERCISED IN CHOOSING A PROPER SOURCE OF SEAL FLUSH TO EUMINATE THE POTENTIAL FOR VAPORIZATION OF THE INJECTED FLUID AND TO AVOID CONTAMINATION OF THE PUMPAGE WITH THE INJECTED FLUSH. ( DIAL THERMOMETER AND ROW INDICATOR ARE OPTIONAL). 

Additional layers are added to the tablet using a grossing solution that is similar to the subcoating formula and contains a colorant. As many as 15 applications may be needed to achieve the target weight of 450 to 490 mg. Warm air (32-38°C) is applied between coats to achieve drying. A dial thermometer is visible to the operator, but there is no requirement to log the actual tempera-... 

The convertor stands 2.35 meters tall, has a base diameter of 0.84 meters and a top diameter of 0.70 meters. It is built of mild steel, typically two to three millimeters thick. Instrumentation includes a process air orifice, and dial thermometers for measuring bed, convertor off-gas and condenser off-gas temperature. 

There are many types of dial thermometers, including liquid, liquid-vapor, or gas filled, and their use is very widespread. These thermometers usually consist of a bulb connected via a capillary tube to a Bourdon tube, which is attached through some mechanism to a movable pointer on a scale. The liquid most commonly used in dial thermometers is mercury. Their inaccuracy may range from 2 to 5°C however, their reproducibility is usually considerably better than that. 

Figure 7-85. For process piping 3-inch and larger, typical thermowell locations. Installation details thermobulb (g), thermocouple (f) (h) (i) and dial thermometers (j) (k) (I).

In Figure 7-86c, two 2-1/2-inch pipe elbows are installed together with a pipe spool piece at the lower end to increase its len h for the installation of a thermowell with a thermobulb. The other elbow adapter holds a dial thermometer in a 6-inch long thermowell. In Figure 7-86d, a single 2-1/2-inch pipe elbow is installed with suitable pipe reducers to fit the small size process line. The 1-inch elbow adapter holds a 6-inch-long well with a thermocouple (T/C). The T/C head is connected with an electrical conduit that carries the circuit to the temperature recorder on the control panel. 

Because the accessories attached to the thermowell may protrude, they must be so instaUed on the piping that they will be parallel with walkways and platforms. If not, a workman carrying tools on his shoulder could accidently knock off the head of a dial thermometer. An operator in an emergency rush could be injured by a T/C head... 

Dial thermometer with pipe thread Immersion length of thermowell Dial thermometer with Vi" pipe th read Immersion length of thermowell ... 

Fig. no. of pipe detail followed by reference to the specific nominal pipe size Indicating dial thermometer with %" dia. bimetallic stem Thermowells for thermobulbs Immersion length starts with dimen-slon given below. Check with the scale shown on fig. Add the length required for the thermobulb. See scale for determining ordering length Thermocouple well... 

The 4-inch swaged-up pipe section with reducers in Figure 7-104 can be connected into small-sized process pipe lines where short thermowells can be installed for dial thermometers and T/C assemblies. 

Ensure all flow and differential pressure indicators etre zeroed and calibrated. All control room pressure indicators need to be checked with a calibrated gage. All dial thermometers and outside pressure gages should be removed and checked for accuracy. The unsatisfactory ones should either be replaced or removed prior to the test and read with calibrated thermocouples, thermometers, or gages during the test. These calibrated devices should adequately fit in the existing fittings. 

Location of plant control room shall be such that it is easy for keeping watch on critical equipments (feeding of raw materials, view glasses, level gauges, dial thermometers, and pressure gauges) even from a distance. These shall have shadow less lights with flameproof casings if inflammable vapours could be present. 

Dial thermometers, standardised temperature measuring instraments ... 

Very low level of oil in the thermowell for dial thermometer—(hence check the oil level regularly). 

Instrumentation Dial thermometers, pressure gauges, pH metre For monitoring of reaction, operation of evaporators, product quality Incomplete reactions, poor product quality Laboratory analysis at every stage to check reaction progress and product quality... 

Local measurements of wet chlorine temperature use tantalum-sheathed flanged thermowells with bimetallic dial thermometers. The insertion length should be selected to place the tip about one third of the diameter into the piping or into an elbow. 

Thermocouples/optical pyrometers/dial thermometers at appropriate places, e.g. on furnace shell, outgoing gas ducts, back surface of refractory bricks... 

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