DeZurik APCO CAC-8000 Istruzioni - Pagina 13

Sfoglia online o scarica il pdf Istruzioni per Unità di controllo DeZurik APCO CAC-8000. DeZurik APCO CAC-8000 17. Automatic control check valve

APCO CAC-8000 Automatic Control Check Valve

Timing Valve Operation (continued)

The Timing Valve Roller when depressed permits oil to flow directly from the Dashpot Cylinder (#63) to

the atmospheric Oil Reservoir, bypassing the Flow Control Valve (#64). The unrestricted flow of oil

allows virtually instant movement of the piston – hence, extremely rapid closure of the Control Valve

Disc (#10). The time period of disc closure is achieved by setting the distance between the Timing

Valve Cam and the Timing Valve Roller closer or further apart from points of contact. Turning the cam

clockwise will increase the distance and hence the time period of contact between the cam roller and

the cam, thus permitting the disc to close at a very fast rate from its full open position toward the

direction of closure. Conversely, turning the cam counter-clockwise will decrease the time period and

distances between contact points of the cam and cam roller, thus permitting the disc to close slower

from the open position toward closure. Alternately, if the cam and cam follower are adjusted so as not

to make contact with each other, the secondary control which is the Flow Control Valve will control the

disc movement from full open to 90% closed.

Slip Gear

The gap between the contact surfaces of the wormwheel and the gear segment is the Slip Gear (see

figure 7). This Slip Gear feature allows the valve to operate as a check valve within this gap.

Operating as a check valve, the dashpot cylinder system fully controls disc movement during either the

opening or closing cycle. The dashpot cylinder system has 3 control stages:

1. Primary Control – Timing Valve (#96) controls the first stage of disc travel.

2. Secondary Control – Flow Control Valve (#64) controls the second stage.

3. Third Control – Built into the bottom cylinder cap, provides the final stage closure of the disc to

shut-off.

The top Flow Control Valve (#64) controls rate of opening of main valve while the bottom control valve

(#64) controls the rate of closing.

The dashpot cylinder system is self-contained. Oil is the controlling media to create a closed system

preventing problems or corrosion, electrolysis and mineral deposits, as results with water operated

dashpots.

The top half of the indicator shows various disc positions. The lower half shows various control

positions (actual position of wormwheel). The two pointers move independently of each other. The

longer arrow points to the disc position, is directly connected to the shaft. The shorter arrow is mounted

on the wormwheel, which rotates freely on the shaft. See Figure 8.

Referring to the control position indicator (lower half), the distance from "check" to "C" is the power

close travel, meaning the valve will control flow in the normal direction, but has the ability to freely

close, if there is a reversal flow. The distance from "check" to "O" is the power open travel, meaning

the wormwheel will force the disc to open, thereby controlling flow in the reverse direction.

December 2012

Page 13

DeZURIK

D12000