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14 Cards in this Set
- Front
- Back
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What type of controls are used to operate and limit a steam boiler? |
Pressure activated switches |
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What is the max pressure setting for a low pressure steam boiler? |
15 psig |
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How should steam boiler pressure controls with mercury switches be connected to the siphon? |
Perpendicular to the siphon |
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Why is a siphon installed on a steam control and not a hot water boiler control? |
To prevent steam entering the control |
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Additive controls control the cut.........pressure Subtractive controls control the cut.........pressure |
Additive controls control the cut in pressure Subtractive controls control the cut out pressure |
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Two types of switch mechanisms used in pressure controls for steam boilers....... |
Micro switch Mercury switch |
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Where would the LWCO be installed on a steam boiler? |
At the boilers MINIMUM SAFE WATER LINE (MSWL) |
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Main scale refers to what? |
Main scale should be set depending on weather the controls are additive or subtractive. Sub out Add in |
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What type of switch mechanism would be found on a hot water boiler |
Mercury or micro switch |
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Minimum return temp on NON condensing boiler.... |
140F Condensing likes lower temp return water to create condensation. |
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Max temp setting for high limit control and why? |
250F To prevent water flashing to steam |
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Two devices that control pressure on a hot water boiler? |
PRV pressure reducing valve SRV safety relief valve |
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LWCO is required only when |
The boiler is over 400,000 BTUs |
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Can a flow switch be used in lieu of a LWCO on a hot water boiler |
Yes |
