Unit 11 Flashcards
T/F
The draft gauge should only be stored in a vehicle so that is is readily available when needed
False. Only when needed as it can be damaged in transportation
What are three temperature reference points for checking temperature measuring instruments?
- 32 F (ice and water)
- 212 F (boiling water)
- 98.6 F (body temp)
T/F
The outer extremities, such as the hands, are not a body temperature
True
How many microns is equal to 1.6 inches of water column on a manometer?
3000 microns
What is the definition of calibration?
Changing the instruments output or reading to correspond to a standard of correct reading
Why are most glass thermometers not able to be calibrated?
Their graduations are etched into the stem
Accuracy is more important in high or low temperatures?
Lower temps. This can translate to larger % errors
A 100 ohm resistor that has a 10% tolerance will measure between _______ and _____ ohms?
90 - 110 ohms
The electric resistance of a heater will be ________ when they get hot.
Greater
How often should combustion analyzers be calibrated?
Wet kits do not need to be calibrated. Electronic analyzers should be calibrated annually.
The potassium hydroxide in the wet kit should be changed after roughly how many tests?
Roughly 200 tests
How often should a volt meter be checked against a high quality bench meter?
Periodically roughly once a year
If the temperature sensing instrument is to be used more than 1000ft above sea level, use a __________ thermometer as a standard instead of the boiling water temperature.
laboratory glass
What is a good investment for use in calibrating electronic thermometers?
Laboratory grade glass thermometer
It is impossible to determine a correct gauge reading if the gauge is not set to _____ at the start of the test
0
Ice made from what type of water is preferred for performing a low temperature check?
distilled or purified water
T/F
The thermometer indicates the temperature of the sensing element, not the temperature of the object or liquid
True
What should be done to the gauge manifold and hoses prior to performing a pressure test?
Open the gauge to atmosphere and check that both gauges read 0 psig
What prevents the needle on the high side manifold gauge from backing up too far when checking a micron gauge?
The high side “bottoms” out at 0 Psig and does not register vacuum. There is also a peg.
If a meter is out of calibration, what is the first thing that should be checked?
Batteries. Then leads that could become frayed
T/F
The boiling point of water is suitable for checking the thermometer in the flue gas kit even though it is near the bottom of the scale
True
To improve the pumping capacity of a vacuum pump, what should be done?
Change the oil
T/F
A small gauge is more accurate for monitoring systems that operate in vacuum because the needle doesn’t have to travel far between 0 psig and 30 inHg
False. Large gauges are more accurate because the needle moves farther from 0 to 30 in Hg.
How can you improve the accuracy of the temperature sensing element?
Insulate and insure good contact. This will prevent surrounding air from skewing readings
In order to check both manifold gauges at the same time, which hose is connected to the refrigerant cylinder?
center yellow hose
How is the meter being checked against the bench meter in Fig. 11.20 connected to the bench voltmeter?
Parallel
