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Series 641 Air Velocity Transmitter

Series AVLV Air Velocity Transmitter

Series 641RM Air Velocity Transmitter with Remote Probe

Questions

Question

We have recently replaced a Dwyer air velocity transmitter (PFS1300204) with a Dwyer Series 641. The new sensor works fine for only a few days and then starts reading almost no flow. These devices are used in an Air Scrubber application (exhaust stack). Is this the right application for the Series 641? I suspect that moisture might be the issue, but I cannot confirm.

Answer

I do not think you are using the 641 series air velocity transmitter in an appropriate application. Any moisture or particulates in the exhaust could be causing damage to the hot wire sensor, leading to the failure. The difference in the sensors is probably why you got longer life out of the PFS series, which unfortunately, is no longer available. The PFS series used a glass filled polyester sensor, which is a little more robust and can with stand the elements a little better. In your specific application, you might take a look at our 641B series which uses a heated mass flow sensor which can be used in dirty air environments.

Related

Series 641RM

Model 641B

Series AVU

Series 641

Question

Is there a minimum duct size that this sensor can be used in?

Answer

The sensing element is about ¾” from the tip of the stem so the duct size would need to accommodate the entire sensing element. If being used in a smaller duct, you will want to verify that the flow range is within the operating range, 1000, 2000, 3000, or 4000 FPM.

Related

Series AVUL

Question

Can you use a display with the Modbus or BACnet options?

Answer

Yes, either the integral LCD Display, A-AVUL-LCD, or the remote display tool, A-435-A, can be used with Modbus or BACnet configurations.

Related

Series AVUL

Question

Is there a minimum duct size that this sensor can be used in?

Answer

The sensing element is about ¾” from the tip of the stem so the duct size would need to accommodate the entire sensing element. If being used in a smaller duct, you will want to verify that the flow range is within the operating range, 1000, 2000, 3000, or 4000 FPM.

Related

Series AVUL

Question

Can the AVPT output volumetric flow readings

Answer

No, the AVPT is configured to output air velocity readings in FPM or M/S only. Consider looking at the AVUL for a unit able to output volumetric air flow.

Related

Series AVPT

Series AVUL

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