Type 311/312 All-Welded “Midi” Diaphragm Seal • All-welded metal construction, prevents leakage of process media • No gaskets or bolts • For use on pressure gauges up to 31⁄2˝ from vac to 1000 psi and 41⁄2˝ gauges 30 psi to 1000 psi • Top housing material 316L stainless steel standard • Diaphragm materials in 316L stainless steel, hastelloy C and tantalum • Bottom housing materials in 316L stainless steel and Hastelloy C • 1⁄4 NPT or 1⁄2 NPT instrument connections • Type 312 furnished with 1⁄8 NPT flushing connection • Type 312 not available in male process connections PRODUCT FEATURES PRODUCT SPECIFICATIONS Model Number: Process Connection Size: All-welded (311) All-welded w/flushing connection (312) Diaphragm Material: 316L SS, Hastelloy C-276, Tantalum Bottom Housing Materials: Instrument Connection Size: Glycerin, Halocarbon, Silicone, Syltherm The compact size of the Ashcroft 311/312 midi-seal allows it to fit into spacerestricted areas and is designed to protect transducers, mini-switches, and 31⁄2˝ or smaller dial size pressure gauges from corrosion, plugging or freeze- up. All-welded metal construction prevents leakage of process media. It is rated for 1000 psi at 100°F and has a 316L stainless steel top housing standard. Lower housing materials include 316L stainless steel or Hastelloy C. Diaphragm materials include 316L stainless, Hastelloy C or Tantalum. 1⁄4, 1⁄2, 3⁄4 or 1 NPT process connection sizes are available. Instrument connection is 1⁄4 or 1⁄2 NPT. Filling Fluid: All specifications are subject to change without notice. All sales subject to standard terms and conditions. ©2016 Ashcroft Inc. 01/16 Ashcroft Inc., 250 East Main Street, Stratford, CT 06614 USA Tel: 203-378-8281 • Fax: 203-385-0408

Type 311/312 All-Welded “Midi” Diaphragm Seal Table A – Process Connection Process Connection Table F – Filling Fluid Glycerin Silicone Pressure Pressure/Vacuum Pressure/Vacuum in presence of strong oxidizing agent Pressure Direct Only Direct or Flexible Line Direct or Flexible Line Direct or Flexible Line Threaded – male NPT* Threaded – male NPT* Threaded – male NPT* Threaded – male NPT* Threaded – female NPT Threaded – female NPT Threaded – female NPT** Threaded – female NPT** Halocarbon Syltherm Monel is a registered trademark of Huntington Alloys, Inc. Hastelloy is a registered trademark...