Parts & Service

Dampers include wear parts which will occasionally need replacement or refurbishment to continue proper operation. Components which should be inspected on a regular basis include: Bearings Packing Actuators Controls, hoses, fittings Senior Flexonics Pathway can supply replacement components and service for other brands of dampers. Factory field installation & service are an ideal way to guarantee proper fit-up and installation of dampers. This service assures you of problem free operation. Many times due to accessibility or cost, refurbishment either on-site or in our shop is a viable alternative to new replacement. Original drawings and/or a site inspection is the first step to assessing the potential. How to Order Parts & Service for PEP dampers, locate the metal name tag, copy the reference drawing number shown on the tag, and contact Pathway Customer Service at (800) 847-5746, info@sfpathway.com or www.sfpathway.com for all other dampers, fax the damper drawing to Pathway Customer Service at (830) 629-6899

Engineering Design Data

Selecting a damper for control of static pressure and flow control

Flow Curves: Based on a 48”ID Butterfly and 42.5”w x 42.5”h parallel blade and opposed blade louver handling 37,630 ACFM (3,000 FPM), 0.040 Lb/Ft3 gas density, 3-blades in each louver damper.

Damper Sealing Efficiency

This curve provides a sealing efficiency comparison between various types of dampers with different seal options. A sealing efficiency of 100% generally requires a pressure-assisted sealing system. Pathway manufactures several designs including the Patented model 362 and 365 butterfly dampers, Pathway model 150C double-louver damper, and model 222, 230, and 266 guillotine dampers. Sealing efficiency for all damper styles can be improved with available options.

Conclusion

Use butterfly dampers when cost is the primary consideration. Selecting seal options is a very inexpensive way to achieve better isolation. Select guillotine dampers in cases where pressure loss is a major consideration. Should 100% isolation be required, select one of Pathway’s many models with the help of a factorytrained application engineer.

Pressure Loss Versus Blade Position

This curve illustrates the advantages and disadvantages of each damper type for static pressure control. Butterfly dampers for round ducts and opposed blade dampers for rectangular ducts provide excellent static pressure control. At midrange blade positions, static pressure can be effectively controlled. This is not the case with parallel blade dampers where pressure control can only effectively occur approaching closed position. Parallel blade dampers are better suited for prespin of gas entering centrifugal fan inlets where gas flow direction favors fan efficiency improvement.

Percent Flow Versus Blade Position

This curve illustrates the advantages of opposed blade dampers and butterflies for fine flow control. These produce nearlinear flow control characteristics as a function of blade position making them ideal for use with positioning devices. Parallel blade dampers provide acceptable flow control exceeding 20-30% full flow. Turbulence produced by parallel blade dampers must be accounted for in the design of duct systems

Percent Open Versus Blade Position

This curve illustrates the differences in open flow area percentage as a function of blade position. From 0 to 30 degrees, butterflies and opposed blade louvers change very little in open area compared with parallel blade louvers. Small changes in open area equate to more precise low-flow control during startup of process systems. From 65 degrees to 90 degrees, parallel blade louvers exhibit better high-flow control since rate of change in open area is less as a function of blade position.

Percent Flow Versus Percent Open Butterfly	Percent Flow Versus Percent Open Opposed / Parallel Blade Louvers

Conclusion

Use opposed blade dampers for control of static pressure or flow in rectangular ducts. Parallel blade dampers should be used for isolation and flow diversion such as for the inlets of centrifugal fans. Butterflies can be used for control as well as isolation where they are especially adept. Specialized applications for flow control include radial vane fan inlet dampers and diverter dampers.

Installation and Testing

Senior Flexonics Pathway is a full service damper company incorporating design, manufacture, inspection, installation, refurbishment and testing services. The installation and start-up of a damper is crucial to the reliability of the equipment. We recommend whenever possible and particularly on critical equipment, that a site installation and start-up commission be considered. This service includes the following items:

factory supervised installation

• Duct squareness
• Flange flatness
• Internal obstructions
• Rigging/installation procedure

Factory Commissioning/Re-Commissioning

This service can also incorporate the following:

• Operator training
• On-site consulting
• Damper evaluations
  • Field
  • In-house

Maintenance

• Actuator calibration
• Seal, seat adjustment or replacement
• Repair
• Inspection

Standard Testing

• Temperature test
• Leak test
• Cycle testing