Product Description

Weight loaded valves are a popular choice for a blower pressure relief valve due to how easy they are to operate and maintain. MaxQ Relief Valves from pdblowers are made in the USA from American steel. The carbon steel construction and metal finishing enamel will keep your valve running smoothly for years to come with minimal maintenance.

MaxQ 4″ Blower Pressure Relief Valve

Connection size is 4″ MPT
Maximum Diameter: 12.97″
Overall Height: 12.3″
Threaded Length: 1.73″
Material of Construction: Carbon Steel
Maximum Allowable Set Pressure: 15 psig
Minimum Allowable Set Pressure: 2.5 psig
Relief Volume at 15 psig: 3,939 CFM
Relief Volume at 2.5 psig: 1,608 CFM

MATERIAL: The valve is made from 1018 American carbon steel with machined and lubricated operating surfaces. A rust inhibiting, corrosion resistant phenolic alkyd resin primer is applied to the exposed steel, followed by a finish coat of high gloss metal finishing enamel. The steel weights are plated with RoHS compliant clear zinc for corrosion resistance.

OPERATION: A weighted cap rides on a machined piston. When the pressure exerted on the cap is greater than the weight of the cap (plus any added weights), the cap rises exposing the ports and allowing air to escape. Once line pressure is reduced, the cap will automatically reseat itself on the piston.

The set pressure of the blower relief valve is modified by adding or removing weights. Each weight represents a 0.5 psi change in set point.  The valve must be sized properly to allow the venting of the excessive flow. If the valve is undersized, excessive pressure could remain in the service line.


INSTALLATION: The relief valve must be mounted in the vertical position to function properly. Overhead clearance must be great enough to allow full travel of the cap. The blower relief valve should be installed on the discharge side of the blower, before any restrictions, and preferably immediately after a silencer if one is used.

MAINTENANCE: Rotate the cap by hand on a monthly basis. Use a light oil on the machined surface of the piston to prevent rust and insure proper operation. The valves are lubricated prior to shipping with pdblowers synthetic blower oil.

SET POINT # of 1/2 PSI Weights Part Number
2.5 PSI 0 MaxQ4.025
3 PSI 1 MaxQ4.030
3.5 PSI 2 MaxQ4.035
4 PSI 3 MaxQ4.040
4.5 PSI 4 MaxQ4.045
5 PSI 5 MaxQ4.050
5.5 PSI 6 MaxQ4.055
6 PSI 7 MaxQ4.060
6.5 PSI 8 MaxQ4.065
7 PSI 9 MaxQ4.070
7.5 PSI 10 MaxQ4.075
8 PSI 11 MaxQ4.080
8.5 PSI 12 MaxQ4.085
9 PSI 13 MaxQ4.090
9.5 PSI 14 MaxQ4.095
10 PSI 15 MaxQ4.100
10.5 PSI 16 MaxQ4.105
11 PSI 17 MaxQ4.110
11.5 PSI 18 MaxQ4.115
12 PSI 19 MaxQ4.120
12.5 PSI 20 MaxQ4.125
13 PSI 21 MaxQ4.130
13.5 PSI 22 MaxQ4.135
14 PSI 23 MaxQ4.140
14.5 PSI 24 MaxQ4.145
15 PSI 25 MaxQ4.150

internal sku: valve body (4PWCS2.5), weight (4PWCS2.5W0.5)

4″ Blower Pressure Relief Valve

BOM Number: MaxQ4 SKU: N/A Categories: ,


  • Meets Build America Buy America Act requirements
Shipping Weight: 36.5 lbs
Shipping Dimensions: 12.97 × 12.97 × 12.3 in

pdblowers, Inc.

Body Materials:

Carbon Steel