PRECISION GAS FLOW METERS & GAS FLOW CONTROLLERS

Frequently Asked Questions

Frequently Asked Questions (FAQs)

Which fittings are recommended for the instruments?

All process connections on the Vögtlin flow meters and controllers have basically BSPP tread (British Standard Parallel Pipe). Within the red-y smart series, red-y compact and red-y industrial series you’ll find ¼” and ½” female tread connections.
BSPP tread also called ISO tread or ISO 228-1. They are often indicated as G1/4″ or G1/2″.

Other threads like NPT or UNF 9/16″-16 are not compatible with the tread on the Vögtlin units. You would need adapters for this. BSPT (Tapered) male tread can be use in female tread, but it’s not recommend. The depth of the treads in the body can be found in the operating instructions (most are 12 mm deep).

You cannot use PTFE tape or liquid sealant. To seal the tread you have to use an O-ring. There are several systems available:

Swagelok/Fitok: Select a fitting with ISO tread and a RS type seal. You need a separate RS gasket for each fitting available in Viton® and Neoprene®.

Serto: Use male adaptor union with Conovor O-ring seal (FKM) f.i model “SO 51124-6-1/4 OR” (with O-ring seal).

Festo push-in fittings: Most G tread fittings have an O-ring, please insure material compatibility.

We strongly recommend to use the dedicated fittings as offered by Vögtlin. You can find details on Compression, Tri-Clamp, Vacuum (identical to VCR®) and Push-in fittings under the “Accessories”-tab on each product page.