Trane Performance Air Handlers Installationshandbuch PDF herunterladen (Seite 82)

82 CAH-SVX01B-EN

Start-Up

Fan Inlet Airflow Measuring System

Wiring

In the absence of a factory-provided control system, consult the transmitter manufacturer or the

factory for wiring.

Note: Ensure that the transmitter has a separate power source.

Transmitter Sizing

The Trane specification requires that the flow meter option have a total accuracy of 5 percent. The

total accuracy is a combination of:

• how accurately the piezometer ring itself is in sensing airflow

• how accurately the transmitter senses the differential pressure

• how accurately the controller translates the signal from the transmitter to a differential

pressure.

Selecting the proper transmitter is critical in order to get accurate airflow measurements using the

piezometer ring. How accurately the transmitter senses the differential pressure is dependent on:

• the pressure range selected

• accuracy of the selected transmitter

Table 6. Back or Top Inlet Traq Dampers - Air-Mixing and Economizer Section - VCM voltage versus airflow at sea level

Part Number

Traq Damper

Size (inches) Quantity Total Area (ft

)

Peak Velocity

(fpm)

CFM @ 10VDC

Peak Velocity L/S @ 10VDC

DMP01123 13 1 0.9213 2500 2303 1087

DMP01124 16 1 1.3956 2650 3698 1745

DMP01663 20 1 2.1806 2650 5779 2727

DMP01125 24 1 3.1400 2700 8478 4001

DMP01126 28 1 4.2739 2700 11540 5446

Figure 77. Piezometer ring airflow

measurement

A fan inlet airflow measuring system with a piezometer ring is available

on many centrifugal and plenum fans. Each system comes with a

differential pressure transmitter. The piezometer ring is connected to the

LO port of the transmitter and the reference pressure point is connected

to (or actually is) the HI port of the transmitter. See Figure 77.

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Trane Performance Air Handlers Installationshandbuch Seite 82