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37 Cards in this Set
- Front
- Back
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What are the 2 common start up methods for steam traps? |
Supervised and unsupervised |
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Where are steam traps required? |
In steam distribution mains at: Elevation changes Low points Long horizontal runs at intervals of 150'-500' Ahead of dead end areas such as shut off valves, temp/pressure controls Ends of mains |
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Where is a drip leg required for an unsupervised start up valve? And supervised? |
Every 150' (unsupervised) Every 300' (supervised) |
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Where should shutoff valves be installed by steam traps and what type should they be? |
On both sides of the trap, gate valves |
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Why should you use one trap per piece of steam equipment? |
Using one trap for multiple pieces if equipment can cause uneven pressure drops and result in air binding and partial flooding. |
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Where should steam traps be located? |
Directly below and as close as possible to the equipment being drained |
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What size should drip legs be? |
Full size of the main up to 4" diameter At least 1/2 the size of the main, but no less than 4" |
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How long should a drip leg be. |
8-10" |
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What are the 3 basic operations of a steam trap? |
Hold back steam Allow passage of condensate Allow passage of non condensable gases |
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What should the pressure be in relation to the inlet and outlet of the trap? |
Inlet = close to the main pressure Outlet = lower pressure |
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What is a steam trap? |
A valve that remains closed to hold back steam and opens to release condensate and non condensable gases |
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What is the order of trim before and after a steam trap on an overhead condensate return system? |
Isolation valve, strainer, union, trap, union, check valve, isolation valve |
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What happens if there is too much condensate in a steam line? |
Water hammer |
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What are the 3 classifications of steam traps? |
Thermostatic, mechanical, and thermodynamic |
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If a corrugated bellows trap fails, what position does it remain in? |
Open |
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What is a cooling leg? |
Uninsulated part of the line before the trap (usually 5' long) |
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What is the benefit of a balanced pressure capsule disc trap? |
Better resistance to water hammer or superheated steam |
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If a bimetallic strip trap fails, is it open or closed? |
Open |
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When a float trap fails, is it open or closed? |
Closed |
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When an inverted bucket trap fails, is it open or closed? |
Closed |
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What type of steam trap is at the end of the steam main on a low pressure boiler? |
Float and thermostatic (F&T) |
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What is the operating load of a steam trap measured in? |
Lbs of condensate per hour |
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What is the safety factor for steam traps calculated as? |
Twice the rated capacity of the heat transfer unit |
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What relationship does the pressure differential across the orifice have with the rate of flow? |
The greater the pressure differential, the greater the rate if flow will be |
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What is the size of a trap designated by? |
The nominal pipe size of the inlet of the trap |
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A traps capacity is based on what factor? |
The operating pressure differential across the trap |
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What is the grade of a line coming off a vertical leg to a trap? |
1/4" per foot |
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What type of trap are considered throttling traps that can open and close in response to the rate at which condensate forms and enters the trap? |
F&T |
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What traps aren't commonly used today because of their inherent design problems? |
Open top or upright bucket traps |
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What is dry saturated steam? |
Steam that is at or above 98% dry |
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What isna drip leg? |
The vertical section of pipe running from the bottom of a main to a trap |
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How far apart on a main should drip legs be located? |
No more than 150' apart |
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On a supervised startup what is the minimum length of a static leg? Automatic startup? |
10" supervised 28" automatic |
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What is a dirt pocket? |
A short length of pipe, usually 6" added below the trap outlet fitting to allow dirt to collect |
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How often should steam traps be inspected? |
Annually |
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What is the most accurate method of determining how well a trap is working? |
Installing a test tee downstream of the trap |
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A continuously flow of condensate or live steam would indicate what? |
The trap is malfunctioning and needs a repair |
