PVDF ventilating valve type 591

  Datasheet (PDF)

The Georg Fischer SYGEF Standard type 591 ventilating and bleed valve is an engineered thermoplastic process control valve manufactured from unpigmented polyvinylidene fluoride (PVDF) for aggressive chemical and ultrapure water applications. Designed for automated venting during pipeline filling and rapid aeration to prevent vacuum collapse during draining, the valve operates via an internal precision-engineered PVDF float mechanism that reacts instantaneously to fluid levels. When air or gas enters the chamber, the float drops to release the accumulated pocket, while rising liquid lifts the float against an FKM elastomeric seal to ensure bubble-tight closure up to a nominal pressure rating of PN16 (SDR21). Covering dimensions d16 to d63 mm (DN10 to DN50), each unit features spigot ends calibrated for socket fusion jointing in accordance with DVS 2207-15 standards. The assembly incorporates a glass-fibre reinforced polypropylene (PP-GF) protective top cap, a compact axial building length, and a true-union construction that permits straightforward installation, in-line inspection, and rapid radial removal without disturbing adjoining pipework. Engineered to withstand high-purity media, deionized water, and harsh chemical reagents across a broad operating temperature spectrum from -20 degrees to +140 degrees Celsius, all injection-moulded wetted surfaces maintain a high surface finish of Ra ≤ 0.5 µm to inhibit bacterial adhesion and particulate entrapment. Compliant with cleanroom manufacturing criteria including FDA 21 CFR 177.2510, USP 25 Class VI, and ASME BPE standards, BigWeld supplies this high-performance degassing component for pharmaceutical water loops and demanding industrial distribution networks.