Device tests

Washington's practical exam uses the USC 10th edition procedures on a five-valve kit, with a sight tube and bleed-off valve supplied. The examiner plants faults on the RP, DC, and PVB and you say what failed. Learn the pass values cold, walk each test in the VR lab until the order is automatic, then run find-the-fault until you can name the failure from the gauge alone.

Reduced pressure principle assembly

Three tests on two hoses (plus the bypass): relief valve opening point, #2 check against backpressure, then the #1 check. The #1 shutoff is never closed.

Walk it through in VRFind the fault

Passes when

Relief valve opens at
2.0 psid or more
#2 check
Holds steady above the relief opening point
#1 check
5.0 psid or more, and above the relief opening point

Steps

Setup

  1. Flush TC4, TC3, TC2 (slowly), TC1, then close them. Don't trip the relief valve.
  2. All kit valves closed. High hose to TC2, low hose to TC3.
  3. Open TC3 slowly, open the low bleed and leave it open.
  4. Open TC2 slowly, open the high bleed to purge air.
  5. Close the #2 shutoff, then the high bleed, then the low bleed. Read the apparent #1 check.

Test 1: relief valve

  1. Open the high control (it stays open).
  2. Hand under the relief port. Open the low control no more than ¼ turn so the needle falls slowly.
  3. Record at the first drip. Close the low control.

Test 2: #2 check

  1. Open the bypass to purge the bypass hose, close it. Bypass hose to TC4, open TC4.
  2. Open the low bleed until the reading is above the apparent #1 reading, close it.
  3. Open the bypass. Passes if the reading holds above the relief opening point.

Test 3: #1 check

  1. Open the low bleed until the reading is above the apparent #1, close it, let it settle.
  2. Record it.

Restore

  1. Close TC2, TC3, TC4. Slowly open the #2 shutoff. Remove hoses, drain the kit.

What you see → what failed

  • Relief discharges nonstop after the #2 shutoff closes, reading near 0→ #1 check leaking; tests can't be completed
  • Reading won't drop to the relief opening point in Test 1→ #2 shutoff leaking
  • Relief opens below 2.0 psid→ Relief valve fails
  • Test 2 reading falls to the opening point twice→ #2 check leaking
  • #1 check under 5.0 psid→ #1 check fails
  • Test 2 reading drifts down slowly→ Disc compression: bleed the low side again

Procedures follow USC's 10th edition as published in its comparison sheets, errata, and state handouts. The USC Non-Illustrated Field Test Procedures booklet is the final word.