Series-FLSTConfiguration

Supported Applications

The Dwyer Series FLST is a duct-mounted airflow measurement station designed for HVAC applications. The system utilizes an averaging element that generates a differential (velocity) pressure signal, similar to orifice and venturi primary elements. Strategically located sensing ports sample total and static pressures when the device is inserted normal to flow; these signals are averaged within isolated chambers before being manifolded together for connection to a differential measurement device such as a gage or transmitter.

Operating Conditions & Performance

The Series FLST measures airflow in air with a range of 100 to 10,000 fpm (0.51 to 51 m/s). Accuracy is within 2% of actual flow when installed in accordance with published recommendations. The station operates at humidity levels from 0 to 100% non-condensing.

Temperature limits for galvanized casings and aluminum elements are:

• 350°F (177°C) continuous operation
• 400°F (204°C) intermittent operation

Configuration Options

The series supports multiple duct configurations including circular, rectangular, and oval stations. Standard construction features a 16 ga G90 galvanized steel casing with 6063-T5 anodized aluminum elements. Process connections are provided via 1/4" compression fittings.

Flange Dimensions

Circular flanges vary by station size "D":

• 8" - 15": .064" thickness, 1" flange size, 6" casing length
• 16" - 44": .064" thickness, 1-1/2" flange size, 6" casing length
• 45" - 72": .188" thickness, 1-1/2" flange size, 10" casing length
• 73" & over: .188" thickness, 2" flange size, 12" casing length

Oval and rectangular stations follow specific dimension tables based on width or height. Oval flanges are optional.

Material Options

The series offers stainless steel configurations via option codes:

• -SS1: 316 SS elements with 16 GA galvanized casing
• -SS2: 316 SS elements with 16 GA 304 SS casing
• -SS3: 316 SS elements with 16 GA 316 SS casing

Additional Options

• -F: Flange (oval stations only)
• -IM: Internal pressure connections (rectangular stations only)

Key Product Differences

The Series FLST is available in circular, rectangular, and oval configurations. Rectangular or oval flow station pressure taps are located on the longer of the two dimensions. Oval airflow measuring stations without flanges have a casing length of 5"; standard oval stations include a 18 gage galvanized casing with an overall length of 7-1/2 inches (including connecting sleeves). The device is not field serviceable and must be returned for repair if needed.