Dwyer Instruments 1221-12-W/M Manometer

The Dwyer Instruments 1221-12-W/M Manometer is a field-proven Flex-Tube U-Tube Manometer designed for the high-precision pressure diagnostics required in heavy-duty HVACR environments. This differential pressure gauge features a 12-inch water column range (6-0-6" w.c.), making it ideal for determining duct static pressure, filter resistance, and fan efficiency. Constructed with 0.375" O.D. clear butyrate tubing, the columns are specifically engineered to be shatterproof and flexible while remaining easy to clean. The scale is built from high-impact polystyrene, ensuring the columns stay in perfect alignment even when subjected to the rigors of a contractor’s tool bag. For technician-level accuracy, the manometer utilizes a high-contrast white scale with silkscreened black graduations, providing 1/10" w.c. minor divisions that are legible from a distance. While typically used with fluorescein green concentrate, this specific "W/M" model is also compatible with mercury, requiring 9.5 ounces of Hg to fill for higher-density pressure readings. This unit is rated for total pressures up to 100 psi (7 bar) and is the industry standard for portable, direct-reading pressure measurement.

• Broad Range Utility: Capable of measuring positive, negative, and differential pressures with a 6-0-6" w.c. scale.
• Shatterproof Construction: Clear butyrate tubing provides the accuracy of a glass U-tube without the fragility.
• Mercury Compatible: Specifically designed to handle the 9.5 ounces of mercury required for specialized high-pressure applications.
• High Legibility: Extra-white scale background with jet-black silkscreened markings reduces common parallax errors during field calibration.
• Complete Kit: Furnished with non-kink vinyl tube connectors and carrying plugs to prevent fluid loss during transport.

Common Questions

What fluids should be used with the Dwyer 1221-12-W/M?
This model is designed for use with water, fluorescein green concentrate (included), or mercury. If using mercury, ensure you have exactly 9.5 ounces for proper zeroing and scale alignment.

Can this manometer be used for high-pressure systems?
Yes, the 1221 series is rated for a maximum internal pressure of 100 psi, though it is primarily used for measuring low-range differential pressures across filters and blowers.

How do you adjust the zero point on the 1221-12-W/M?
The scale is adjustable. Open both fittings to the atmosphere, add your fluid until it reaches the approximate zero mark, and then slide the scale to align the zero line exactly with the fluid meniscus.

This item is not eligible for free shipping.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.