DeZurik APCO AVV-1800 Buku Petunjuk - Halaman 9
Jelajahi secara online atau unduh pdf Buku Petunjuk untuk Unit Kontrol DeZurik APCO AVV-1800. DeZurik APCO AVV-1800 18 halaman. Dual body combination air valve with optional csv surge check valve
Halaman Cetak
APCO AVV-1800/1800K Dual Body Combination Air Valve
Maintenance (Continued)
4. Assemble cover (R2) and attached components to body (R1), installing new gasket (R3) if
necessary. Tighten bolts (R4) opposite each other in rotation.
Air/Vacuum Valve 1-20" (25-500mm) Only
See Figures 2-3 for part identification.
5. Install bumper (A40) and float (A14) in body (A1).
6. Clean surface of recess in cover (A2) and install seat (A6) with seat screws (A16/A34).
7. Assemble cover (A2) and gasket/O-ring (A3) to body (A1). Tighten cover bolts (A4) opposite
each other in rotation.
8. Install and secure pipe plug.
Testing
See Figures 2-6 for part identification.
9. Perform a seat test. Restore pipeline pressure and slowly fill the Air/Vacuum valve chamber
by cracking open the isolation valve below Air/Vacuum Valve. If seepage occurs once the
float (A14) or needle (R7) is in contact with the seat (A6/R6), reference to the "Disassembly
Procedure" and replace seat, needle, and/or float.
10. If there is no seepage during the seat test, fully open isolation valve.
Operation
Combination Air Valves prevent accumulation of air at high points within a system by exhausting large
volumes of air as the system is filled and releasing accumulated pockets of air while the system is
operational and under pressure. They also prevent potentially destructive vacuums from forming by
admitting large quantities of air into the system caused by power outage, water column separation or
sudden rupture of the pipeline. Additionally, these valves allow the system to be easily drained because
air will re-enter as needed.
The Surge Check Valve operates on the interphase between the kinetic energy in the relative velocity
flows of air and water. The Surge Check is a normally open valve, spring loaded, so that air passes
through unrestricted. When water rushes into the Surge Check Valve, the disc begins to close against
the spring tension and reduces the rate of flow of water into the air valve by means of throttling holes in
the disc. This ensures normal gentle closing of the Air/Vacuum Valve regardless of the initial velocity
flows involved and minimizes pressure surges when the valve closes.
As soon as the Air/Vacuum Valve is closed, the pressure on both sides of the Surge Check Valve disc
equalizes and the disc automatically returns to the open position. This means the Air/Vacuum Valve
does not need an incipient vacuum to open, but can open at any time the water level drops and line
pressure approaches atmospheric. This allows immediate full re-entry flow of air into the pipeline before
a vacuum can form. The Air Release Valve is a hydro-mechanical device that automatically vents small
pockets of air as they accumulate at high points in a system while operating under pressure.
This type of valve should not be considered as a relief for shock conditions which develop elsewhere in
the system. However, actual field tests prove the Surge Check Valve may protect the Air/Vacuum Valve
from damage by severe shut-off shock.
June 2019
with CSV Surge Check Valve
Page 9
DeZURIK
D12025