Hi Gerard. The two piece check valves are hydraulically locked together as required by the standard. For serviceability we recommend the 3 piece check valve which is designed specifically for this.
“These 2 piece check valves are ideal for low pressure condensate lines. ordered one day and normally turn up the next. great service, easy to order, simple web site even for an old fart like me to use to find what I need, check stock and price and order.”
