Retrotec DM-2A Manual de usuario descargar pdf (Pagina 49)

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In extreme cases, wind dampening kits split the main pressure pickup point into either two or four

directions, which will average the fluctuation across the building. Recent experience has shown that

longer time averaging on a digital gauge is almost as effective as the four tube wind damping kit. When

the time taken to set up the kit is taken into account, increasing the time averaging will actually save

time.

Overall, what works best is to have one tube running outdoors, where it is T’d into two equal length

tubes that are placed as far away from the building as possible.

7.5 Time Averaging User Errors

While the Time Averaging feature is useful to help minimize the effects of wind, it can also cause

problems if not used correctly. Whenever Time Averaging is on, it is important to wait at least twice

the time averaging period before taking a reading.

To learn how Time Averaging can cause error

1. Create a pressure on the positive port of Channel A (Input).

2. Set Time Averaging to one minute.

3. Wait until the pressure reading becomes stable. After one minute, Channel A should display

the created pressure.

4. Remove the tube from Channel A, eliminating the pressure.

5. Notice that the gauge continues to display a pressure on Channel A, which slowly decreases.

After one minute, the gauge should display no pressure difference.

If a reading is taken from the gauge before the full time averaging period has passed, then the

displayed pressure may not be accurate.

7.6 Large fixed errors

A pinched pressure tube can create a very high reading on the gauge, which is erroneous. In other

cases, a pinched tube will prevent the pressure measurement from reaching the gauge at all. In cases

where tubes get stepped on, they are seldom sealed off completely, but will still cause the gauge

readings to jump around. If the gauge begins to display an unusually high or unexplained pressure,

check the tubing to ensure that it has not been compressed in any way.

Figure 12. Errors in pressure reading from a pinched tube.

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Retrotec DM-2A Manual de usuario Pagina 49