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The most consequential decision in exit hardware specification is not brand, not finish, and not function. It is channel. The channel determines whether the device is mechanically compatible with the door, whether it latches at one point or two, whether the rods are visible on the door face, and whether installation requires standard surface mounting or door factory modification. Specifying a concealed vertical rod device on a solid core wood door requires either returning the hardware or rebuilding the door. Specifying a rim device on a double-door opening without an astragal leaves a gap that defeats the latching purpose entirely.

What an Exit Device Channel Means

An exit device consists of a crossbar, a latch mechanism, and the channel, which is the mechanical path through which the latching function is delivered. The channel determines latch point count, visibility of rods on the door face, door construction requirements for installation, and the relative security level of the device.

Rim Exit Devices

A rim exit device mounts on the door face. The crossbar connects to a rim latch at the door edge that engages a rim strike mounted on the frame doorstop. Single-point latching at the door edge. Rim devices are the most widely stocked, most widely serviced, and most broadly available in aftermarket parts of all exit device channels. They are the correct specification for single doors in standard hollow metal or wood frames, light to medium traffic openings, and retrofit applications on doors without vertical rod channel preparation.

The limitation of rim on double-door openings without an astragal is that the gap between the two door panels at mid-panel height allows the panels to flex past the edge of the rim latch with moderate force, bypassing the single-point latch. For those applications, SVR or CVR is required.

The panic exit device selection at National Lock Supply covers rim configurations from Von Duprin, Sargent, and PHI in stock for same-day shipping.

Surface Vertical Rod (SVR) Exit Devices

An SVR device uses a crossbar connected to two vertical rods running up and down the door face, one to a top latch at the frame header and one to a bottom latch at the floor or threshold. Both rods retract simultaneously when the crossbar is depressed. Two-point latching eliminates the panel-flex vulnerability on double-door openings without an astragal.

SVR is the correct specification for double-door openings without a center post, for single high-security doors requiring two-point latching, and for retrofit applications on doors without factory CVR channels. The bottom rod strike mounts at the floor or threshold, and the Pemko saddle threshold guide covers threshold selection for compatibility with SVR bottom strikes.

Complete SVR configurations including matching top and bottom rods, strikes, and threshold covers are available as exit device kits at National Lock Supply.

Concealed Vertical Rod (CVR) Exit Devices

A CVR device routes the vertical rods through the interior of the door rather than on its face. From the interior, the door appears to have only the crossbar hardware visible. CVR provides the mechanical security of two-point latching with the appearance of a single-point device.

CVR requires a hollow interior channel from the crossbar location to both the top and bottom edge of the door. This limits CVR to hollow metal doors with factory rod channels and hollow core wood doors with sufficient internal space. Solid core fire doors cannot accommodate concealed rod routing. The door factory must have the CVR manufacturer's template before fabrication. CVR costs 20 to 40 percent more than equivalent SVR devices in unit price, plus factory door preparation cost.

Mortise Exit Devices

A mortise exit device integrates the crossbar mechanism with a full mortise lock body installed in the door edge. The mortise body contains both the latch bolt and a separate deadbolt. The through-bolt construction, full steel lock case, and separate deadbolt function provide forced-entry resistance that rim and vertical rod devices cannot match. Mortise exit devices are specified for government buildings, financial institutions, healthcare behavioral units, corrections facilities, and any application where maximum forced-entry resistance is required.

The exit device trims guide covers exterior access trim selection for mortise exit devices including lever trim, pull handle, and electrified trim options.

The Channel Selection Matrix

For double-door openings with an inactive leaf secured by flush bolts, a rim device on the active leaf is the correct specification. The flush bolts and coordinators specification guide covers inactive leaf hardware for these applications.

Fire Rating by Channel

All four channels are available in fire-rated configurations. Rim has the broadest UL listing coverage, with Von Duprin, Sargent, and PHI carrying 3-hour ratings for steel door assemblies. SVR is available with UL fire rating from major manufacturers. CVR fire-rated devices exist but the selection is narrower; confirm fire listing before specifying CVR on a fire-rated door. Mortise fire-rated exit devices are available from Sargent and Von Duprin, but the mortise pocket in the door must not compromise the door's listed fire rating.

Exit Device Trim: The Next Decision

Once the channel is selected, the trim determines exterior access. The top 10 panic bar trims guide covers the most widely specified trim products for each channel type, including lever trim with key cylinder for keyed exterior entry, pull handle trim, and electrified trim for access control integration.

Brands by Channel

Von Duprin: dominant specification in rim and SVR. 98/99 series rim and 2227/2228 SVR are the institutional standards. Detex: exit alarm and exit alarm with exit device combinations for secondary exits requiring alarm monitoring. Corbin Russwin: ED4000 rim and ED5000 SVR, strong in New England and Mid-Atlantic institutional specifications. PHI (Precision Hardware): 2100 rim, 2200 SVR, and 4100 CVR value-tier institutional options.