Five Slot Shapes on a Sprinkler Deflector Designing Around the Shadow Cast by the Frame Arms

This application covers the small slotted disc that sits under a fire sprinkler and turns a jet of water into a spray pattern. The claimed sprinkler has a deflector plate cut with several different shapes of slot, arranged so that the slots sitting directly beneath the two frame arms are flanked on each side by a distinctive club shaped slot that reaches further in toward the centre than the others. It was filed by Victaulic Company, the American manufacturer that invented the grooved pipe coupling, and names Thomas F. Wancho as inventor. The application is the latest in a chain of Australian divisionals running back to a 2018 United States provisional.

The Problem

The driver here is warehousing. As the specification puts it, growth in the storage market has pushed up not only floor area but ceiling heights and the density at which goods, called commodities in the trade, are stacked. Early suppression fast response sprinklers, known as ESFR, were developed in the 1980s specifically for that challenge, and they are graded by k factor, the constant relating discharge rate to the square root of pressure. Standardised values of roughly 14, 17 and 25 are the exemplars, and higher k factors are used as ceilings get taller.

The specific problem the specification names is high clearance. A warehouse with a ceiling at forty feet may rack its goods only to twenty feet, leaving a twenty foot gap between the sprinkler and the thing that is burning. Anything over ten feet of gap counts as high clearance, and a change to UL’s UL 1767 standard now requires k factor 17 and above sprinklers to demonstrate they can handle it in a live fire test.

Over that distance a spray pattern spreads out and thins. The specification describes the three things a sprinkler has to do at once: keep a dense, fast core flow directly under itself, keep an outer umbrella wide enough to cover the required area, and keep enough water in the intermediate zone between the two that a fire there cannot grow and overwhelm the umbrella. A pattern that disperses too widely loses density in exactly that intermediate band.

Worse, updrafts from the fire plume can lift and disrupt the outer umbrella, which then wets and cools the sprinklers next to it. Those cooled heads do not open. The specification calls this skipping, because the heat plume skips the nearest and best placed sprinklers and instead triggers more distant ones that are less effective. The result is more fire damage, more water damage, more risk to firefighters, and in the worst case a protection system that is overwhelmed.

What This Invention Does

Claim 1 describes a fire suppression sprinkler in the usual arrangement: a body surrounding a bore that defines a flow axis, first and second frame arms on opposite sides of the body extending along that axis and together defining a plane, a nose on the ends of the arms, and a deflector plate mounted on the nose transverse to the flow axis, with a periphery surrounding a centre on the axis.

The claimed detail is entirely in the slots. There are slots of a first configuration running from the periphery radially inward and terminating at a first distance from the centre, with at least two of them lying in the plane of the frame arms, that is, directly beneath the arms. There are at least four slots of a second configuration terminating at a second distance, positioned so that one sits adjacent to each side of each of the first configuration slots that lie in that plane. There are slots of a third configuration terminating at a third distance. Claim 1 then imposes two conditions. The second distance must be less than either the first or the third, so the flanking slots reach deepest toward the centre. And the second configuration slots must be club shaped, meaning a handle extending in from the periphery and a club head whose width nearer the handle is less than its width nearer the plate centre.

The reason is stated openly in the detailed description. The frame arms are a discontinuity in the flow leaving the bore, an effect the specification calls frame shadowing, and the arms cast that shadow onto the deflector directly below them. Putting the slots with the largest surface area, and the ones that cut deepest toward the axis, immediately beside the slots that sit under the arms is described as compensating for it. Conversely, remote from the arms, where the flow is already uniform, the specification places slots that are symmetric about their radial lines.

The worked embodiment has five slot types rather than three, and their placement is precise. Arrow shaped slots align with the two arms at 180 degrees apart. A second pair of arrow slots sits at 90 and 270 degrees from them. Four club shaped slots occupy 22.5, 157.5, 202.5 and 337.5 degrees, flanking the arm slots. Four asymmetric arrow slots sit at 45, 135, 225 and 315 degrees, and four elongate keyhole slots at 67.5, 112.5, 247.5 and 292.5 degrees. The example sprinkler is an ESFR head with a k factor described as about 17 to 34, and specifically 25.2.

Claim 22 is a second independent claim covering an early suppression fast response sprinkler in pendent orientation with a bore of k factor 25.2 or greater, a removable plug over the bore, and the nose mounted less than one inch from that plug. Claim 3, dependent on claim 1, covers the k factor 14.0 or greater pendent case.

Key Features

• Slots keyed to the frame arms. At least two slots of the first configuration lie in the plane defined by the two frame arms, so the slot pattern is registered to the physical obstruction rather than merely spaced evenly around the plate.
• Club shaped flanking slots. The four slots either side of the arm aligned slots have a handle and a club head that widens toward the plate centre, and in the worked example they carry the largest surface area of any slot type on the plate.
• A deliberate depth hierarchy. Claim 1 requires the flanking slots to terminate closer to the centre than either of the other two slot configurations, concentrating the deepest cuts where the frame shadow falls.
• Asymmetry near the arms, symmetry away from them. The club slots and the arrow slots nearest the arm plane are asymmetric about their radial lines, while the keyhole and arrow slots furthest from it are symmetric, matching the plate geometry to how uniform the incoming flow already is.
• Arrow slots wider than the arms. The arrowhead of each arm aligned slot is specified as being equal to or wider than the thickness of the arm above it, so the slot does not simply sit in the arm’s shadow but exceeds it.
• A deflector spaced off the arm ends. The nose carries a cylindrical flow conditioning portion that extends past the arm ends, holding the plate at a gap described as more than twice, and preferably about three times, the plate thickness.

Who Is Behind It

Victaulic Company is a privately held American manufacturer headquartered in Easton, Pennsylvania. Its origin is the grooved mechanical pipe coupling, patented in 1919 by Ernest Tribe and Henry Hele-Shaw, which joined pipe with a bolted clamp and a gasket rather than welding or threading. The name itself comes from the victaulic joint, and the company has since built out a large fire protection line alongside its pipe joining business, with manufacturing plants and branches worldwide. Its fire product range spans sprinklers, valves, preaction and deluge devices, and the water and nitrogen Vortex suppression system.

Thomas F. Wancho has been working on sprinkler heads for a long time. He appears as co inventor with Claude Bosio on a sprinkler deflector application filed in 1996 by The Reliable Automatic Sprinkler Co, and later on Victaulic filings including an extended coverage ordinary hazard sprinkler system and this deflector family. The problem he is solving in this specification, how a stamped disc redistributes a jet into a fire suppressing pattern, is the same one, three decades on.

The priority chain is set out in full at the head of the body text, which is unusual for this batch. The specification states that this application is a divisional of Australian application 2024201949, which was a divisional of 2022201347, which was a divisional of 2019232686, the national phase entry of PCT/US2019/019213 filed 22 February 2019, which claims priority to United States provisional application 62/640,208 filed 8 March 2018. That makes the priority country the United States and the effective priority date more than eight years before this filing.

Why It Matters

Sprinkler deflectors look like an odd thing to patent. They are stamped metal discs a few inches across, and there is no moving part and no electronics anywhere in claim 1. But the deflector is the only component that decides where the water goes, and in a warehouse forty feet up that decision is the entire performance of the system. Everything upstream, the pipework, the valves, the pump, exists to deliver pressure to a hole; the plate turns that into a fire suppression pattern or it does not.

The regulatory context is what gives the geometry its commercial value. NFPA 13 sets what may be installed where, while UL and FM Global run the live fire tests that decide whether a given head qualifies. The specification is candid that the target is not merely passing the minimum criteria but exceeding them, because a head approved for tighter aisles than the standard minimum unlocks denser storage for the building owner. The stated example is approval at a ceiling height up to forty eight feet, commodity height up to forty three feet, and aisle spacing down to four feet. Four foot aisles in a forty eight foot warehouse is a meaningful amount of extra rentable pallet space.

Frame shadowing is also a nice illustration of how mature engineering problems get solved. The frame arms cannot be removed; they hold the nose that holds the trigger and the deflector. So the specification does not try to eliminate the discontinuity, it maps it and then cuts the plate asymmetrically to compensate, with the biggest slots where the shadow is worst and symmetric slots where the flow is already even. The claimed invention is not a new mechanism at all. It is a pattern of holes that admits the machine has a flaw and arranges itself around it.

Related Concepts

• Fire sprinkler system – the pipework, valves and water supply the claimed sprinkler head terminates.
• Automatic fire suppression – the broader category of systems that act without human intervention, of which ESFR sprinklers are one branch.
• National Fire Protection Association – the body behind NFPA 13, the installation standard that governs where each k factor of sprinkler may be used.
• UL) – the certification organisation whose UL 1767 standard sets the live fire test this design is aimed at.
• Nozzle – the fluid mechanics category the bore and deflector combination belongs to.

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AU 2026202143 was published in the Australian Official Journal of Patents on 9 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.