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Air Velocity

Air Velocity
Dwyer offers wind meters that have the option of pocket wind meters and handheld meters. There are also wind speed indicators and vaneometers that are designed to simplify the measurement of low air velocities. Air velocity transmitters are sold in this category as well, which are ideal for monitoring air flow.

QUESTIONS

Question
Can the Vaneometer model 480 be equipped with a scale to read in inches of water? We want to use the vaneometer to assure we have a pressure differential of -0.01 wc when measured at the door gap to a patient isolation room.
Answer
The series 480 does not come with a scale reading in inches w.c., the scales would be in velocity units to read air velocity. However, we do have differential pressure gages or manometers than can be used to measure the differential pressure in an inches w.c. scale. I would recommend taking a look at our Series 2000 Magnehelic® Differential Pressure Gage, as we do have many customers use these for clean room applications. We have the model number 2000-00N which has a range of 0-0.2. and the major grads will be 0.01” w.c.
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.
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.
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.
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.