null
close
close
click to zoom in
  • Guaranteed Fitment

    Always the correct part

  • In-House Experts

    We know our products

  • Added Value

    Fast & Reliable

  • US & Canada Delivery

Dwyer 641B-4 Air Velocity Transmitter (250-2000 fpm)

No reviews yet Write a Review
$1,265.36
SKU:
641B-4
Condition:
New
Availability:
In Stock
5 customers are viewing this product

Dwyer 641B-4 Air Velocity Transmitter (250-2000 fpm)

$1,265.36

Dwyer 641B-4

Features

  • Provides an isolated 4-20 mA output proportional to the velocity
  • Steel sensor allows the unit to be used in dirty air environments
  • This rugged sensor is ideally suited for quick field cleaning from a simple cloth to a pulse of air from an air source
  • Proper sensor performance can be maintained in these polluted environments by easily removing dust and debris from the sensor which is problematic for Pitot tubes and other flow sensing transmitters
Specifications
  • Service: Air and compatible, non-combustible gases
  • Accuracy: 5% FS Process gas: 32 to 122°F (0 to 50°C)
  • 6% FS Process gas: -40 to 32°F & 122 to 212°F (-40 to 0°C & 50 to 100°C)
  • Response Time: Flow: 1.5 seconds to 95% of final value (output filter set to minimum)
  • Temperature Limits: Process: -40 to 176°F (-40 to 80°C). Ambient: 32 to 140°F (0 to 60°C)
  • Humidity Limit: Non-condensing
  • Power Requirements: 12-35 VDC, 10-16 VAC. 1.5 A rating required on supply due to initial power surge drawn by transmitter
  • Output Signal: 4-20 mA, isolated 24V source, 3 or 4-wire connection
  • Output Filter: Selectable 0.5-15 (seconds)
  • Loop Resistance: 600 ohms max
  • Current Consumption: 300 mA max
  • Electrical Connections: Screw terminal
  • Enclosure Rating: Designed to meet NEMA 4X (IP66)
  • Mounting Orientation: Unit not position sensitive
  • Weight: 12.6 oz (357.2 g)

Anemometers are instruments used to measure wind speed or air velocity in meteorology and aerodynamics. The name is derived from the Greek root Anemos, meaning wind. There are many anemometer sensor types with one of the most popular being thermo, or hot-wire, anemometers for HVAC/R air velocity monitoring. Thermo-anemometers use a sensor element that is heated up beyond the ambient temperature. Airflow moving past the sensor will have a cooling effect that is directly proportional to the flow velocity.

Hot wire anemometers come in three basic types: constant current, constant voltage, and constant temperature. All three types have circuits that are based on trying to maintain a specific variable during the cooling effect based on Ohm's Law. Thermo-anemometers offer good low flow detection, fast response times, and high rangeability of measurements. They are omni-directional, making them good for turbulent flows and easier to use than pitot tubes, but are more fragile than pitot tubes.

Usually, a probe style sensor is made for insertion into ducts and pipes. For constant temperature thermo-anemometers, two temperature sensors are installed at the end of the probe, typically resistance temperature detectors (RTDs). One RTD measures the ambient temperature as a reference. The second RTD is continuously maintained at a constant temperature above ambient. The higher the air velocity, the more current is required to maintain the second RTD's temperature. Based on the current usage, the air velocity is calculated.

Like a pitot tube, thermo-anemometers are a single point sensing device that requires being in the center of the velocity profile or the use of traverse readings for accurate measurements.

Includes Dwyer 641B-4

  • Dwyer 641B-4 Air Velocity Transmitter (250-2000 fpm)
Shipping & Return
Returns Policy

All returns must be authorized. Items returned prior to authorization will not be accepted. For international customers where applicable, customers must ship any returns to us freight and duty prepaid. Return freight charges for internationsl shippments will be the responsibility of the customer.

Defective new equipment may be returned for warrantyrepair/exchange to us within (5) days of the shipment receipt date. After five (5) days, returns will be handled by direct contact and in accordance with the warranty terms of the item's manufacturer. Items that have malfunctioned due to mishandling, electrical overload, etc., will be subject to repair charge.

Non defective new equipment will be authorized for return within five (5) days of the shipment receipt date if the equipment is still in new, re-sellable condition with the original manual(s), accessories, packing material and carton. We reserve the right to reject returnsin which there is no original packaging, missing accessories, damage or visible signs of usage of the item. A restocking fee of up to 25% of purchase price may apply. Special orders and dangerous goods are non-returnable.

(Do not write anytingon the manufacturer's original package or use as a shipping carton. Include all accessories, manuals and warranties.)

Please, include a copy of the packing list or invoice with a reason for the return. Your return authorization number is valid for thirty (30) days.

Shipping

We can ship to both US and Canada. Note that there are restrictions on some products, and some products cannot be shipped to international destinations.

When you place an order, we will charge a flat rate shipping for your items.

Please also note that the shipping rates for many items we sell are weight-based. The weight of any such item can be found on its detail page. To reflect the policies of the shipping companies we use, all weights will be rounded up to the next full pound.

Not Applicable

Condition: NA

Frequently Asked Questions

  • How do I request a quote?
    To request a quote for pricing on any item found on our site, please click on our "REQUEST A QUOTE" link. Fill out and submit the form, one of our representatives will contact you when the quote is ready.
  • What payment options do I have?
    EquipTestPro accepts a variety of payment options for your convenience. For prepayment, we accept all major credit cards (MasterCard, Visa, Amex, Discover), Purchase Orders, and wire transfers.
  • How do I retturn items?
    All returns must be authorized. Items returned prior to authorization will not be accepted. For international customers where applicable, customers must ship any returns to us freight and duty prepaid. Return freight charges for internationsl shippments will be the responsibility of the customer.

    Defective new equipment may be returned for warrantyrepair/exchange to us within (5) days of the shipment receipt date. After five (5) days, returns will be handled by direct contact and in accordance with the warranty terms of the item's manufacturer. Items that have malfunctioned due to mishandling, electrical overload, etc., will be subject to repair charge.

    Non defective new equipment will be authorized for return within five (5) days of the shipment receipt date if the equipment is still in new, re-sellable condition with the original manual(s), accessories, packing material and carton. We reserve the right to reject returnsin which there is no original packaging, missing accessories, damage or visible signs of usage of the item. A restocking fee of up to 25% of purchase price may apply. Special orders and dangerous goods are non-returnable.

    (Do not write anytingon the manufacturer's original package or use as a shipping carton. Include all accessories, manuals and warranties.)

    Please, include a copy of the packing list or invoice with a reason for the return. Your return authorization number is valid for thirty (30) days.

Canada & US Shipping
Rewards Program
Secure Shopping
30-Day Free Returns