100-123 Flashcards
100.How can you determine if a water gauge glass is properly set? SPO 6-7-8
By filing the boiler with water to normal operating level and measuring the depth of the water to the top row of tubes.
101.How high above the top row of tubes in an H.R.T. boiler must the lower gauge cock be set to have a safe amount of water at this point? SPO 6-7-8
At least 3” above the top row of tubes.
102.Name three appliances that can warn you of low water. SPO 6-7-8
Water sight glass
Low water alarm
Fusible plug
103.If your boiler has only one low water cutoff what is the ASME code requirement? LPB 2-3
That it must have a manual reset.(Side Note: The City of Omaha requires one to be a manual reset even if you have 2 cutoffs. If there is repair work done on the boiler there must be a manual reset added)
104.What is the purpose of a high fire limit control on a boiler? What is a modulating control? BOW 2-3-4
It proves that the forced air damper has fully opened prior to starting the pre-purge period to insure adequate purge air flow.
It adjusts the firing rate of the burner to maintain the boiler steam pressure.
105.Is an automatic shutoff allowed between the boiler and the water column? SPO 6-7-8
NO! Only between the water column and the gauge glass.
106.What type valves are allowed between the boiler and the water column? SPO 6-7-8 BOW 2-3-4
ONLY O.S. & Y. or Stopcocks which are locked or sealed open!
Outside screw and yoke
107.Name two types of fusible plugs. SPO 6-7 LPB 2-3 BOW 2-3-4
FIRESIDE & WATERSIDE. This refers to the side where they are installed.
108.What is a bourdon tube? SPO 6-7-8 LPB 2-3 BOW 2-3-4
The Bourdon tube consists of a curved tube with an oval cross section. One end is attached to the frame and pressure connection. The other end is attached to a pointer, linkage and gears. An increase in pressure tends to straighten the tube; its motion is transmitted to the pointer.
109.What is a siphon tube and what is it used for? SPO 6-7-8 LPB 2-3 BOW 2-3-4
A siphon tube or pigtail loop protects the mechanism of the gauge from live steam
110.What pressure range should a steam gauge be when used on a boiler? SPO 6-7-8 LPB 2-3 BOW 2-34
It should be a compound gauge at least 1½ times the maximum allowable working pressure.
111.Where is the steam gauge connected to the boiler? How do you properly mount a steam gauge to a boiler? SPO 6-7-8-LPB 2-3 BOW 2-3-4
It is mounted either on top of the water column or to the top of the steam drum.
A gauge is mounted with a siphon tube, isolation valve and test connection.
- Name three types of feedwater regulator systems. SPO 6-7-8 BOW 244
- MODULATING such as thermohydrolic or thermodynamic.
- ON/OFF, Such as a float probe.
- METERING as a 2 or 3 element.
113.Why is a boiler feed pump used on some boilers and not others
You will not need a pump if the operating pressure of the boiler is below city water pressure.
114.What is the most important valve on a boiler? SPO 6-7-8 LPB 2-3 BOW 2-3-4
The SAFETY valve.
115.What is a safety valve and how does it operate? SPO 6-7-8 LPB 2-3 BOW 2-3-4
It is a device to expel all excess steam pressure from a boiler. The huddling chamber causes the valve to open fully and quickly, causing a definite drop in pressure before closing.
116.A safety valve is limited to how many square feet of heating surface? SPO 6-7-8 LPB 2-3 BOW 2-3-4
Any boiler with more than 500 sq. ft. of heating surface must have 2 or more safety valves.
117.If a safety valve lifts at 100 psi what pressure should it close? What are the requirements governing safety valve blowdown? SPO 6-7-8 BOW 2-3-4
96 to 98 PSI
Safety valve shall operate without chattering, with a blow down of not more than 4% of the set pressure and in no case, less than 2 pounds.
118.How do you determine if a boiler has sufficient safety valve capacity? SPO 6-7-8 LPB 2-3 BOW 2-34
The ACCUMULATED test determines if the valves will discharge all the steam generated by the boiler without allowing the pressure to rise more than 6% above the maximum allowable working pressure of the boiler.
119.How must a safety valve be connected to the boiler? SPO 6-7-8
- Independent of any other steam connection.
- Close as possible without any unnecessary piping.
- Screwed into the boiler shell or fastened to a flange welded to the shell.
- Connected to stand upright.
- Vents must be fastened to the building and not connected to the valve.
120.At what temperature does a safety valve on a superheater have to be protected with heat resisting materials? SPO 6-7-8
450 degrees F.
121.How do you regulate the blowdown of a safety valve? SPO 6-7-8 LPB 2-3 BOW 2-34
The blowdown is adjusted by adjusting the blowback ring, the spring or both about 10%. Only trained and licensed personnel should adjust safety valves.
122.How often is it recommended to test your safety valves manually and how often under pressure? BOW 2-3-4
Every 30 days manually and Yearly under pressure
123.How is a superheater protected? SPO 6-7-8 BOW 2-34
Each Superheater must have one or more safety valves near their outlet with the pressure set below those on the boiler insuring a constant flow of steam through the Superheater.
