48 Questions
What is the purpose of a boiler water level indicator?
To continuously measure and display water level
According to ASME BPVC I Part PG-60.1, how many gage glasses are required for boilers with a maximum allowable working pressure exceeding 400 psi (3 MPa)?
Two gage glasses
Why do boilers with a maximum allowable working pressure exceeding 400 psi require two gage glasses?
To ensure redundancy in case one gage glass malfunctions
Which type of method includes gauge glasses for determining boiler water level?
Direct method
What is the minimum distance required between the lowest visible water level and the lowest permissible water level in a gage glass, according to ASME BPVC I Part PG-60.1?
2 inches (50 mm)
According to ASME BPVC I Part PG-60.1.1.1, what can be provided instead of one of the two required gage glasses?
A remote water level indicator
What is the purpose of the water column in relation to the gauge glass?
To dampen agitation in the water and act as a reservoir
What does ASME BPVC I Part PG-60.1 state regarding the lowest visible water level in a gage glass?
It should be at least 2 in. (50 mm) above the lowest permissible water level.
What causes eventual failure of tubular gauge glasses?
High temperature chemically treated water
What should be done if the gauge glass leaks when put into service?
Close the steam and water valves on the gauge before tightening the nuts
What type of gauge glass is used for higher pressures, exceeding about 3000 kPa?
Flat gauge glass
What does the discolouration of mica coating in a transparent gauge glass indicate?
Failure of the mica, and that water is now directly contacting the glass
Why does cracking open the steam valve and leaving the drain valve open heat the gauge glass slowly?
To avoid sudden temperature changes
Which type of gauge glass is suitable for temperatures exceeding 250°C and pressures up to 70,000 kPa?
Transparent gauge glass
What is indicated by the presence of armoured glass in transparent and reflex gauge glasses?
Ability to withstand high temperatures
What can cause a high water level in the gauge glass of a boiler, fooling both operators and controllers into believing the boiler is full of water?
Blocked water connection piping causing condensate accumulation and obstructed return to the boiler
What is the purpose of maintaining unobstructed water and steam connections to both a water column and a gauge glass in a boiler?
To ensure proper communication of the boiler water level to the level instruments
Under what conditions does ASME BPVC IV Part HG-604 prohibit isolation valves in steam heating boilers?
When steam and water piping have isolation valves
What is the recommended frequency for blowing down gauge glasses on smaller high-pressure boilers?
Blow down every shift
What should be done if gauge glasses become obscured by internal corrosion or deposits?
They should be renewed
What is the purpose of remote water level indicators in a boiler?
To show the water level at a remote location
According to ASME BPVC I Part PG-60.1.1.1, what is required if the water level in at least one gage glass is not readily visible to the operator?
A combination of two independent continuous transmission and display of an image of the water level in a gage glass
What happens when the drum level rises in the remote water level indicator shown in Figure 24?
The diaphragm rises and moves the shutter upwards so more blue shows
What keeps a constant head of water pressure on one side of the manometer shown in Figure 25?
A condenser at the boiler drum
What happens to the shutter in the remote level indicator shown in Figure 24 when the drum level drops?
It moves upwards to show more red color
What is used to transfer the optical image of the water level to the control area when it's not readily visible to the operator?
A fiber optic cable or mirrors
What happens to the pressure in the remote water level indicator when the level in the boiler steam drum is at a minimum?
The pressure differential between the two heads will be the greatest.
What is an advantage of a remote water level indicator?
It has no moving mechanical parts.
What is the purpose of dirt traps in a remote water level indicator?
To prevent contamination of the indicating liquid.
What can happen if indicating liquid is overfilled in a remote water level indicator?
The indicated level will be too high.
What do electronic remote water level indicators use to sense and transmit level?
Various methods
Where can one or more remote LED displays be located in a typical electronic water level gauge system?
Up to three different locations
What type of signal does a digital water level indicator receive from a drum level transmitter?
Standard 4 to 20 mA signal
How are positive or negative readings indicated in a loop-powered digital water level indicator?
In millimetres
"In order for any remote water level indicator to be used to meet the requirements of ASME BPVC I Part PG-60.1.1.1," what must it be designed and installed to meet?
"The requirements of ASME BPVC I Part PG-60.1.1.2"
What is monitored in real time by cameras transmitting information to a central control room?
Water levels
According to ASME BPVC I Part PG-60.1.1.2, what should not be excluded from being used as operator aids?
Other remote indication devices like cameras and loop-powered indicators discussed
What is the recommended method of tightening the nuts on the cover when replacing the flat gauge glass?
Starting at the centre and tightening evenly on both sides
Why is it recommended to never reuse old gauge glasses?
Old glasses may have weakened glass surfaces
What is the purpose of using molybdenum disulfide on the contact surfaces of the new glass during replacement?
To allow the glass to slip into place easily
What causes many gauge glass failures on high-pressure boilers?
Inadequate heating of the new glass
What does a bicolour gauge glass indicate with different colors for steam and water?
The water level at a distance
What is the purpose of connecting a hooded mirror to a bicolour gauge glass as shown in Figure 23?
To reflect light to another mirror on the operating floor
What is indicated by the presence of armored glass in transparent and reflex gauge glasses?
Resistance to both mechanical and thermal shock
What is indicated by a dark area in a reflex gauge glass?
Water level in the gauge glass
According to ASME BPVC I Part PG-60.1.1.1, what is required if the water level in at least one gage glass is not readily visible to the operator?
Installation of mirrors for transferring optical image
What type of gauge glass is suitable for temperatures exceeding 250°C and pressures up to 70,000 kPa?
Armored-type gauge glass
What does ASME BPVC I Part PG-60.1 state regarding the lowest visible water level in a gage glass?
It should be slightly above the lowest permissible water level
Learn about the safety precautions and best practices for handling flat gauge glasses to prevent glass failure. Understand the importance of using the crossover method for tightening bolts and the suitability of flat gauge glasses for various applications.
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