BAT Tools & Equipment Operation 2 — Questions and Answers
Question 1: When zeroing a differential pressure gauge before a field test, the tester should ensure the gauge reads zero with:
- Both bleed valve and needle valves open to atmosphere (Correct answer)
- Both high and low side hoses connected with test cocks closed
- Only the high-side hose pressurized
- The gauge disconnected from all hoses
Correct answer: Both bleed valve and needle valves open to atmosphere
Zeroing is performed with all valves open to atmosphere so no pressure acts on either side of the gauge.
Question 2: A field test kit gauge that reads 2.0 psid when both sides are open to atmosphere requires:
- Recalibration or replacement before use (Correct answer)
- A manual offset adjustment recorded on the test report
- The reading to be subtracted from all test results
- No action if within a 5 psid tolerance
Correct answer: Recalibration or replacement before use
A gauge that does not read zero at zero differential must be recalibrated or replaced to ensure accurate test results.
Question 3: Which hose connection color convention is standard on most differential pressure test kits?
- Red = high pressure, Blue = low pressure (Correct answer)
- Blue = high pressure, Red = low pressure
- Yellow = high pressure, Green = low pressure
- Color coding is not standardized across manufacturers
Correct answer: Red = high pressure, Blue = low pressure
The industry convention is red for high-pressure (upstream) and blue for low-pressure (downstream) connections.
Question 4: When testing a reduced pressure zone (RPZ) assembly, the differential pressure gauge needle valves are used to:
- Control the rate at which water enters the gauge to protect it from pressure spikes (Correct answer)
- Increase system pressure during the test
- Vent the assembly relief valve manually
- Measure static water pressure at the inlet
Correct answer: Control the rate at which water enters the gauge to protect it from pressure spikes
Needle valves throttle water flow into the gauge, preventing sudden pressure surges from damaging the gauge internals.
Question 5: A tester's differential pressure gauge has a full-scale range of 15 psid. During an RPZ test, the zone differential reads 13.5 psid. This situation calls for:
- Using a higher-range gauge to avoid operating near full scale (Correct answer)
- Accepting the reading because it is still within range
- Multiplying the reading by a correction factor
- Re-testing with system pressure reduced by half
Correct answer: Using a higher-range gauge to avoid operating near full scale
Operating a gauge near its full-scale limit reduces accuracy; a higher-range gauge should be used for readings above roughly 75% of full scale.
Question 6: What is the primary purpose of the bleed valve on a backflow test kit?
- To release trapped air and water from the gauge hoses before taking a reading (Correct answer)
- To shut off water supply to the assembly under test
- To simulate downstream backpressure conditions
- To check the calibration of the needle valves
Correct answer: To release trapped air and water from the gauge hoses before taking a reading
The bleed valve purges air from the hose lines so readings reflect true water pressure rather than air compression errors.
Question 7: A tester notices that the low-side hose of the test kit is kinked during an RPZ test. The most likely effect on the differential pressure reading is:
- An artificially high differential reading because low-side pressure is restricted (Correct answer)
- An artificially low differential reading because high-side pressure drops
- No effect because only the gauge internals affect the reading
- The relief valve will open prematurely
Correct answer: An artificially high differential reading because low-side pressure is restricted
A kinked low-side hose restricts pressure transmission to the low side of the gauge, making the differential appear larger than actual.
BAT Tools & Equipment Operation 2
When zeroing a differential pressure gauge before a field test, the tester should ensure the gauge reads zero with: