The Von Duprin 900508 is the OEM center case mounting package of 2 for the Von Duprin 5547, 5547-F, and 5575 exit device series, documented in the Von Duprin 55 Series Exit Device Parts Manual. The package contains two 12-24 x 1/2" OPHMS (Oval Point Hex Machine Screw) fasteners that secure the center case to the door face. Finish must be specified - these screws have an oval-domed hex socket head that is visible at the center case mounting positions on the door, so the finish must match the installed device.

This is a pack of 2 and is in stock without lead time.

What the Center Case Mounting Package Secures

The center case is the core mechanism housing of the 55 Series exit device - it mounts on the door face and houses the latch retraction mechanism that connects to the vertical rod or cable system driving the top and bottom latches. Every time the push bar is depressed, force transmits through the center case mechanism, through the vertical system, and out to the latch engagement points at the door frame header and threshold.

The 900508 mounting screws are the fasteners holding the center case against the door surface at two mounting points. Getting these right matters in more than one way. The OPHMS (Oval Point Hex Machine Screw) is specifically designed for this application - the oval dome head sits flush and finished against the cover plate surface, providing a clean appearance while the hex socket drive allows precise installation torque without cam-out. Using the wrong screw type (Phillips, slot, or flat head) at this location creates both a performance problem (inconsistent seating, stripping risk) and an aesthetic problem (mismatched head profile against the finished cover).

The pack of 2 covers one complete center case installation - one screw per mounting position.

Von Duprin 5547 and 5575: 55 Series Device Configurations

The 5547 is the Concealed Vertical Rod (CVR) variant of the Von Duprin 55 Series exit device family. In a CVR configuration, the vertical rods connecting the center case to the top and bottom latches run inside the door cavity rather than on the door surface. The door edge shows no exposed rod hardware, making the 5547 the preferred specification for aluminum frame and glass-heavy applications where surface-mounted rods would create an aesthetic conflict.

The 5547-F is the fire-rated version of the same CVR device, carrying UL listing for fire-labeled door assemblies under positive pressure testing.

The 5575 is the mortise version of the 55 Series - the latch mechanism integrates with a mortise lock body at the door edge rather than using a separate rim latch or vertical rod system. The mortise configuration provides a flush door edge with no protruding surface-mounted hardware. The 5575 uses the same center case mounting footprint as the 5547, which is why the 900508 mounting package covers all three configurations from one part number.

Von Duprin Exit Device Parts: 55 Series Center Case Hardware

The Von Duprin 55 Series Parts Manual lists the center case mounting package as a field-replaceable unit. Center case mounting screws are the components most likely to strip or corrode on high-cycle exterior installations or in environments with moisture exposure - coastal facilities, outdoor corridor doors, and food service applications where cleaning chemicals contact the door hardware regularly.

When the mounting screws fail, the center case can develop play at its mounting positions. Even minor movement between the center case and the door face introduces misalignment in the vertical rod or cable system, which changes the engagement geometry at the top and bottom latch strikes and eventually causes unreliable latching. Replacing the 900508 screws proactively at first sign of looseness restores rigid center case positioning before the rod alignment problem develops.