Idex VHP Unions for Capillary Tubing

VHP Unions for Capillary Tubing

  • Featuring stainless steel bodies and PK/PEEK™ fittings
  • Pressure rated up to 15,000 psi (1,034 bar)
  • Options to direct-connect both 1/32” OD tubing and 360 μm OD tubing

Upchurch ScientificR has expanded its line of specialized fittings and connectors for UHPLC applications to include several innovative unions and adapters.

Two of these products — the UH-432 and UH-436 — follow the design of our popular Mini MicroFilters (see page 165) and allow a convenient union between either 1/32” OD tubing or 360 μm OD tubing. Each features a stainless steel union body and a unique stainless steel union capsule, enabling both excellent chemical compatibility as well as conductivity, making these a great choice for electrical interfacing in certain LC-MS applications. Each is also coupled with direct-connect ferrules made from our proprietary PEEK polymer blend (PK), allowing tubing connections up to 15,000 psi (1,034 bar). (Please Note: While these connectors can be used at elevated pressures, they are not recommended for applications above 100°C.)

The UH-632 is a more traditionally designed connector, incorporating internally threaded ports. The union (UH-632) features a true ZDV (zero dead volume) connection between both tubes. This unique product is coupled with our one-piece Ultra-High Performance Fingertight fittings manufactured from our proprietary PEEK polymer blend, allowing them to be used in high temperature applications (up to 200°C) at pressures up to 6,000 psi (414 bar) — or use these connectors at room temperature up to 15,000 psi (1,034 bar)!


Application  NOTE:

What is a True ZDV Union?

True zero dead volume (ZDV) unions are designed so that the two joined pieces of tubing butt perfectly together as shown in the image to the right. These products have no swept volume contained within the union body. The fluid moves directly from one tube into another in this type of connector. When using true ZDV unions, it is important to take care to ensure connecting tubing has burr-free 90 degree ends. Find tubing cutters on page 74 to assist with cleanly cutting polymer and fused silica tubing. Gauge plugs are supplied with True ZDV Unions to assist with assembly. With the gauge plug inserted into one side of the union, a hard stop is created for the tubing to bottom out against as it is connected to the opposite port. The gauge plug is removed and then the second piece of tubing is connected, using the first piece of tubing to bottom out against resulting in the two tubes joined together in the center of the union.

Serial Number



VHP MicroTight® Union 1/32


VHP MicroTight® Union for 360µm OD


VHP MicroTight® Union 6-32 ZDV