Edition du 24/02/09
/ 12 U508217-e Revision : 2
4
SECTION 2. DESCRIPTION
A. GENERAL
1. The Series 7889 Meter Preset is used in fluid flow
applications where it is desired to close a valve after a
predetermined amount of liquid has passed through.
2. In technical terms, the Preset is a non-repeating,
predetermining counter that is driven by and normally
mounted on a flow meter. It has a two-stage output
that is normally used to close a valve in two stages.
3. The Preset is used in combination with other
Veeder-Root meter accessories.
B. SPECIFICATIONS.
1. Input. The Preset is driven by a rotating shaft from a
customer-supplied flow meter. The type of input
coupling should be specified when ordering. Maximum
torque to drive the Preset through a knockoff is 40
ounces per inch. Average running torque is below 4
ounces per inch.
2. Mounting. See Figure 1. There are eight tapped
mounting holes for use with ¼-28 screws. The Preset
is designed to mount directly on a.
3. Valve and Switch Connections. The Preset can be
connected to a two-stage valve by customer supplied,
direct linkage or by an electrical switch with linkage.
Either linkage connects to a rotating knockoff plate on
the bottom of the Preset case with a 114-28 screw
(Figure 1). The rated first-stage valve load is 60
pounds.
4. Outline Dimensions. See Figure 1.
5. Flow Rate. The maximum speed of the right-hand
wheel (least significant digit) is 250 rpm. With a 1:1
ratio between the input and the right-hand wheel, the
maxi- mum input speed would also be 250 rpm. If one
revolution of the right-hand wheel represents 10
gallons, the maxi- mum flow rate would be 2500
gallons per minute. Gear plates are available to
provide various ratios of input revolutions of the right-
hand wheel.
6. Preset Number. 4 or 5 digits. Preset in additive
direction by individually actuating five preset buttons
(maximum preset capacity 99999)
7. Display. 4 or 5 wheels with ½ inch white digits on
black background.
8. Output (Knockoff). Two-stage knockoff. Unit
counts down from preset number. First stage knockoff
point is set at the factory to customer's specification at
90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5,4, or 3.
An option al three-finger rake provides first stage
knockoff at a number between 900 through 100 in
increments of 100. The setting can be internally
changed by the customer in the field. Second (final
stage) knockoff occurs when aIl wheels reach zero.
See Figure 1 for angular travel of knockoff plate.
9. Interlock. The Preset has a unique interlock feature.
The Preset buttons cannot be actuated until the SET
button is depressed (latched). The SET button cannot
be latched with the valve load applied. Therefore, the
preset number cannot be changed while fluid is
flowing.
WARNING: IF THE PRESET OPERATING HANDLE IS
MOUNTED IN THE 5 O'CLOCK POSITION, THE HANDLE
COULD STRlKE THE OPERATOR'S HAND WHEN
DEPRESSING THE EMERGENCY STOP BUTTON.
10. Emergency Stop. The STOP button will "dump"
both first and final stages of the valve to provide
complete shutdown.
11. Options. Presets are available with a Series 7856
explosion-proof switch for use with electrically
operated valves. The Preset can be integrally mounted
to a Veeder-Root Meter Register or to a Meter Register
with Ticket Printer.
Figure 1. Dimensions
