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PRGM7-TV-SS-AF1F2系列
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| DIAL-A-FUNCTION® Design Features Various U.S. and Foreign patents and patents pending. ®Registered trade name |
How it Works
Why Dial-A-Function
Additional Dial-A-Function Benefits
Dial-A-Function Manifolds vs. Manually Sequenced Manifolds
Theory of Operation
An Improved Design Lowers Costs:
Dial-A-Function instrument manifolds and valves are engineered to reduce downtime and service costs by guarding ... the accuracy of the flow and pressure control systems ... the personnel from unsafe conditions ... and the hardware within the system.
| How it Works: |
Dial-A-Function is a unique multi-function soft seat rotary valve design that allows the operator to simply dial the service mode, thus assisting him in the responsibility of opening and closing a number of valves in exactly the right sequence.
| Why Dial-A-Function?: |
A manually sequenced 3 valve manifold has 8 possible valve positions. A 5 valve manifold has 32 possible positions, each with even more sequences to arrive at the proper service mode. With this large number of variables, there is an unnecessarily high probability of human error.
Problems caused by improper valve position or sequence:
| ERROR A The equalizer is left open or is opened before the block valve is fully closed (caused by operating the manifold with two hands). PROBLEM:
DIAL-A-FUNCTION SOLUTION: This error is theoretically impossible with Dial-A- Function. The high pressure signal is automatically blocked before the equalizer is opened. |
| ERROR B The equalizer is not fully closed or is leaking. PROBLEM: A very deceiving and false transmitter output resulting in inaccurate measurement or control. DIAL-A-FUNCTION SOLUTION:
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| ERROR C While pressurizing, a block valve could be opened before the equalizer is opened. PROBLEM: Full process pressure would hit one side of the transmitter causing shifts in zero and span or permanent damage. DIAL-A-FUNCTION SOLUTION:
Interlocking Protection Solution to Error C: During startup, without the IP option, if the operator fails to rotate the BLOCK handle to NORMAL before the ZERO handle is rotated to NORMAL, error C will occur. The IP option mechanically interlocks the valves, causing the BLOCK VALVE to simultaneously rotate to NORMAL while the ZEROING VALVE is being rotated. The IP option guards against static pressure hitting one side of the transmitter causing loss of calibration or damage. |
| ERROR D A block valve could be left closed when returning to service. PROBLEM: The transmitter will now be measuring pressure instead of flow. This will result in major measurement and control problems. DIAL-A-FUNCTION SOLUTION:
Interlocking Protection Solution to Error D: If the ZERO handle is left in the BLOCK mode, the output of the transmitter would be zero (4mA) and the operator would be alerted to the problem. If only the ZERO handle is returned to NORMAL, the mechanical linkage automatically returns the BLOCK handle to the NORMAL mode. This reduces the possibility of the manifold trapping pressure resulting in a transmitter output of pressure rather than flow. |
| ERROR E The equalizer could be left closed while a vent valve on one side of the transmitter was opened to depressurize the system. PROBLEM: Full process pressure would remain on one side of the transmitter causing shifts in zero and span or permanent damage. DIAL-A-FUNCTION SOLUTION:
Interlocking Protection Solution to Error E: During depressurizing, without the IP option, if the operator fails to select the ZERO mode before the DEPRESSURIZE mode, error E will occur. The IP option mechanically links the valves so, as the BLOCK handle is rotated to the DEPRESSURIZE mode, the ZERO handle is automatically rotated to the ZERO mode. The transmitter is protected from damage caused by full process pressure remaining on one side during depressurizing. |
| Additional Dial-A-Function Benefits: |
- The operator can visually inspect the manifold from a distance to determine the operating mode by looking at the position of the large arrowhead handles.
- Dial-A-Function reduces the time required to service a system.
- An Interlocking Protection (IP) Option is available to give maximum operator assistance to overcome errors which can cause transmitter damage, inaccuracy and unsafe conditions.
| Dial-A-Function vs. Manually Sequenced Valves: |
| Type of Manifold | Manually Sequenced Manifolds | DIAL-A-FUNCTION | |
|---|---|---|---|
| 3 Valve | 5 Valve | Interlocking Protection (IP) Option Mechanically interlocks the valves to protect the transmitter from damage and inaccuracy caused by an error in valve position or sequence. | |
| Number of valve positions | 8 ( 2 3 ) | 32 ( 2 5 ) | Dial-a-Function has only the required number of positions (2 to 7), specified by model. |
| Selection of position and sequence | Position and sequence are selected by the operator. | Automatic positioning and sequencing of the selected function. | |
| Probable errors due to improper position or sequence | 1. Transmitter damage 2. Inaccurate measurement or control 3. Unsafe conditions | 1. None (after system is pressurized) 2. IP Option guards the system even during startup | |
| Theory of Operation: Model MM6UC |
| 1) NORMAL 2) ZERO 3) DEPRESSURIZE 4) ISOLATION 5) AND/OR CALIBRATION 6) REPRESSURIZE 7) RETURN TO NORMAL | Note the logical sequence of handle positions as you select the modes necessary to advance from NORMAL through CALIBRATEand then return to NORMAL (Steps 1 to 7). This is the same order of modes you would need on a manually sequenced manifold. However, to accomplish this with a manually sequenced manifold, you would need to know which of the 3 valves to open or close and in what sequence. With a DIAL-A-FUNCTION manifold you just dial the next position ... forward or reverse and you will automatically be in the correct mode. Certain models can also be used to test for equalizer leakage as shown below: TEST EQUALIZER LEAKAGE How to Test Equalizer Leakage With IP Option:
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