Flow Batching-
One Valve or Two

Durant

Many production processes involve dispensing a certain amount of fluid, either as an ingredient to be mixed with other ingredients to make a batch of product, or as the end product itself to fill containers for shipping. If the batch size is small, or infrequently mixed, the fluid may be added manually, like adding a cup of milk to a batch of pancake mix. This will be impractical in most industrial applications. In industrial applications, a closed-loop dispensing system consisting of a flowmeter, a batch control, and one or two solenoid valves, will be necessary.

Unlimited potential for any OEM who builds machinery for batching or filling, or any end user where a fluid is dispensed by the batch, such as:

1. Food processing

2. Animal feed production

3. Concrete batching

4. Tank farms

5. Chemical production

A bit more detail: In operation, the process or machine operator enters a preset number of gallons, or liters, or pounds, etc. into the batch control, and presses the start key on the control. The control energizes an internal relay, which opens the valve, and flow commences. The batch control then counts out the amount of fluid that has been dispensed until it reaches the preset amount, at which time it de-energizes its relay, closing the valve. At any time during the batch delivery, the operator should be able to press the stop key on the batch control, causing the relay to de-energize and stop the delivery. The operator can then either resume batch delivery from the point where it had been stopped, or reset the batch by using keys on the control.

When the control closes the valve at the end of the batch, normally some overrun will occur. This is due to the fact that the valve cannot close instantaneously.

Our solution: When precise delivery is necessary, a second valve may be used. The second valve is in a smaller pipe and bypasses the first valve (see diagram). This method uses both of the Eclipse batcher�s control relays in a classic pre-warn application. A pre-warn preset is entered along with the batch preset. When the operator presses start (already included with the Eclipse, no need for separate start/stop pushbutton), both relays energize and both valves open. The control counts up until the amount delivered is equal to the batch preset value minusthe pre-warn value and then shuts off the main valve. The dribble valve remains open, and flow continues, but at a reduced rate. When the amount delivered equals the batch preset value, the control shuts off the dribble valve.

A variation of the two valve pre-warn application occurs when the Eclipse batch control is used to control a single valve and a pump. The pre-warn relay controls the pump, while the final relay controls the valve. When the operator presses the start key, the valve opens and the pump starts. The pump is shut off at the pre-warn volume prior to the valve being closed. This can save wear and tear on the plumbing.

Eclipse Batcher as a Closed-Loop Flow Control

Eclipse Batcher in Team Process Control

Eclipse Flow Display for a Fan or Pump Application

Eclipse Flow as a Signal Conditioner

(Flow Transmitter)