KF (QF) HV Reducer Tees: Reliable Transitions in High-Vacuum Plumbing
KF (QF) HV Reducer Tees are specifically designed to provide dependable, leak-tight branching in high-vacuum (HV) systems where two ports of the same size need to be connected to a third of a different diameter. These fittings serve a critical function in applications that require T-shaped plumbing but must also accommodate varying KF flange sizes across the ports. Whether integrated into a foreline pump circuit, chamber port configuration, or instrumentation setup, reducer tees offer unmatched versatility and performance.
At TFM, we manufacture KF (QF) tees using high-purity tubing and precision-machined flanges to ensure full compatibility with standard vacuum hardware. These tees are optimized for both through-line and foreline vacuum plumbing tasks, making them a common feature in laboratory-scale HV chambers, research instrumentation, and industrial vacuum systems.
KF (QF) HV Reducer Tees are available in a variety of size configurations, including popular options such as KF40 to KF25 or KF25 to KF16. The reducer design simplifies system layout by eliminating the need for additional adapters or couplers, helping maintain streamlined gas flow and minimizing overall connection points. This not only improves system integrity but also reduces turbulence and the chance of contamination or backstreaming in critical processes.
Our standard KF tees are offered in two primary materials to suit a wide range of application needs. For most high-vacuum applications, 304L stainless steel is used due to its corrosion resistance, mechanical strength, and low outgassing properties. For non-corrosive environments or lightweight system requirements, we also offer standard KF (QF) tees in aluminum 6061-T6—though reducer tees are typically constructed in stainless steel for structural integrity and vacuum tightness across size transitions.
One of the key advantages of TFM’s KF (QF) HV Reducer Tees is the flexibility in design. While standard tees feature identical flange sizes across all ports, the reducer tees are intentionally manufactured with two different flange diameters—typically with one branch port smaller than the straight-through ports. This design allows seamless transition between different system components, facilitating the integration of smaller gauges, instruments, or sublines into a larger vacuum structure without the need for separate reducing adapters.
To further meet specific application requirements, we offer custom fabrication services. While common tube lengths and flange sizes are listed in our catalog, we understand that high-vacuum systems are rarely one-size-fits-all. Our engineering team is available to collaborate on your custom specifications—whether you need non-standard lengths, tube diameters, special weld finishes, or electropolished internal surfaces for ultra-clean systems.
KF (QF) HV Reducer Tees are compatible with all standard quick-flange (QF) hardware, including centering rings with elastomer or metal O-rings, and wing-nut or clamp-style KF fittings. The result is a reliable, tool-free assembly that supports fast installation and disassembly—an important advantage in research and industrial settings where system uptime and flexibility are critical.
In summary, KF (QF) HV Reducer Tees from TFM provide a high-performance, compact solution for bridging different flange sizes within a vacuum system. Their robust material options, vacuum-compatible fabrication, and adaptability make them ideal for both simple and complex HV setups. Whether you’re branching a foreline, adding an instrumentation tap, or expanding your system architecture, these reducer tees offer dependable functionality with precision fit and finish.
Ordering Table
| Flange Size/OD (Large) | Flange Size/OD (Small) | Type | Flange Material | Drawing | Tube OD (Small) | Tube OD (Large) | Note | Part Number |
| KF25 (1.57" OD) | KF16 (1.18" OD) | Reducing Tee | 304L SS |
| 0.75 | 1.00 | — | QF25X16T |
| KF40 (2.16" OD) | KF16 (1.18" OD) | Reducing Tee | 304L SS |
| 0.75 | 1.50 | — | QF40X16T |
| KF40 (2.16" OD) | KF25 (1.57" OD) | Reducing Tee | 304L SS |
| 1.00 | 1.50 | — | QF40X25T |
| KF50 (2.95" OD) | KF16 (1.18" OD) | Reducing Tee | 304L SS |
| 0.75 | 2.00 | QF50X16T | |
| KF50 (2.95" OD) | KF25 (1.57" OD) | Reducing Tee | 304L SS |
| 1.00 | 2.00 | — | QF50X25T |
| KF50 (2.95" OD) | KF40 (2.16" OD) | Reducing Tee | 304L SS |
| 1.50 | 2.00 | — | QF50X40T |
Accessories Table
| Description | For | Per Package | Part Number |
| Cast Clamps (SS) | KF10, KF16 Flanges | 1 | QF16-075-CS |
| Cast Clamps (SS) | KF25 Flanges | 1 | QF25-100-CS |
| Cast Clamps (SS) | KF40 Flanges | 1 | QF40-150-CS |
| Cast Clamps (SS) | KF50 Flanges | 1 | QF50-200-CS |
| Cast Clamps (Aluminum) | KF10, KF16 Flanges | 1 | QF16-075-C |
| Cast Clamps (Aluminum) | KF25 Flanges | 1 | QF25-100-C |
| Cast Clamps (Aluminum) | KF40 Flanges | 1 | QF40-150-C |
| Cast Clamps (Aluminum) | KF50 Flanges | 1 | QF50-200-C |
| Lever Clamps (Aluminum) | KF10, KF16 Flanges | 1 | QF16-075-CHA |
| Lever Clamps (Aluminum) | KF25 Flanges | 1 | QF25-100-CHA |
| Lever Clamps (Aluminum) | KF40 Flanges | 1 | QF40-150-CHA |
| Centering Ring (SS with Fluorocarbon O-Ring) | KF10 Flanges | 1 | QF10-050-SRV |
| Centering Ring (SS with Fluorocarbon O-Ring) | KF16 Flanges | 1 | QF16-075-SRV |
| Centering Ring (SS with Fluorocarbon O-Ring) | KF25 Flanges | 1 | QF25-100-SRV |
| Centering Ring (SS with Fluorocarbon O-Ring) | KF40 Flanges | 1 | QF40-150-SRV |
| Centering Ring (SS with Fluorocarbon O-Ring) | KF50 Flanges | 1 | QF50-200-SRV |
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