Pressure relief doors are specialized duct access doors that release the buildup of excessive pressure in ductwork. These products respond to changes in system pressure by opening to let air in or out. This protects ductwork from damage caused by excessive positive or negative pressure, saving facilities from expensive and time-consuming repairs to crucial systems.

How Does Excessive Pressure Build Up in Ductwork?

Positive Pressure: Positive pressure buildup occurs on the supply side of ductwork. When blockages occur downstream of supply fans and blowers, the buildup of positive pressure can cause ductwork to buckle or explode.

Negative Pressure: Negative pressure buildup occurs on the exhaust or return side of ductwork. When airflow is constricted upstream of exhaust fans, the immense negative pressure can cause ductwork to crumple.

How Do Pressure Relief Doors Correct Pressure Differentials?

Mechanical Latch: Pressure relief doors feature fully mechanical, adjustable latches that automatically respond when differential pressure in the ductwork reaches a pre-set threshold.

Piano Hinged Door: When the mechanical latch detects pressure levels have reached the threshold, pressure relief doors open up on a piano hinge to let air out (for positive pressure relief doors) or in (for negative pressure relief doors).

Coiled Return Springs: After the positive or negative pressure differential is relieved, coiled return springs return pressure relief doors to their closed position—no manual resetting required.

What Are the Benefits of Specifying a Pressure Relief Door?

Works Automatically: Pressure relief doors require no electrical connection to work, automatically opening and closing thanks to the mechanical systems underpinning their design.

Protects Sensitive Systems: Pressure relief doors safeguard sensitive and delicate ductwork components and systems from damage due to excessive pressure buildup.

Cost-Effective: Replacing damaged ductwork is a costly affair that often requires opening up the ceiling for access. Pressure relief doors intervene before damage can occur, saving facilities time and money.

How To Specify a Pressure Relief Door

KEES Positive Pressure Relief Duct Access Door
KEES Negative Pressure Relief Duct Access Door

Materials

  • Galvanized Steel: A sturdy, cost-effective material commonly used to make pressure relief doors.

  • Stainless Steel: A heavy-duty, corrosion-resistant material chosen for facilities that work with harsh chemicals.

Insulation

  • None: Most common in exhaust ductwork, where loss of heated or cold air due to thermal transfer isn’t a concern.

  • 1”: Minimum level of insulation to counteract thermal transfer in supply and/or return ductwork.

  • 2”: Thicker insulation that better counteracts thermal transfer.

Additional Options

  • Viewport: A viewport included on the pressure relief door to perform visual checks into the ductwork.

  • Round Duct Mounting: Both positive and negative pressure relief doors can be manufactured for round ductwork.

Why KEES

Investing in safety is guaranteed to pay dividends. KEES positive and negative pressure relief doors are a one-time purchase that protects ducktwork from devastating and costly damage, returning savings over and over. KEES works with clients to factory pre-set our pressure relief doors to the exact pressure rating they need, ensuring doors spring into action just as pressure buildup becomes critical. We offer a wide range of sizes—including custom sizing—guaranteed to fit any ductwork. Trust KEES pressure relief doors to take the pressure off the safety and operations of ductwork systems.

Learn more about KEES Positive Pressure Relief Doors and Negative Pressure Relief Doors.