■The rod packing is divided into three pieces or six pieces, made of either a combined-type special carbon or fluorocarbon resin, and tightened by a garter spring. Like the ring, the best-suited materials are selected.
■Since the gland packing is designed so that the pressure in the cylinder is led as pilot pressure to the backside of the packing, the self-sealing effect is excellent and almost no gas leaks.
Distance piece arrangement
Type 1(Single distance piece)
Suitable for inert gases and air
Single chamber is provided between the cylinder and the crankcase.
Type 1 distance piece consists of cylinder pressure packings for minimizing gas leaks from cylinders and oil seels for eliminating oil running along with piston rod , and completely isolates cylinders and crankcase for oil-free operation.
Type 2(Double distance piece)
Suitable for flammable gases and toxic gases
Double chambers are provided between the cylinder and the crankcase.
In addition to the cylinder pressure pacling , the intermediate partition packings are provided to eliminate even small amount of leakage from the cylinder pressure packing.
Outboard distance piece can be vented to disporsal area , and inboard distance piece can be purged by inert gas and then vented to the atmosphere.
For high purity gas services which is very easily affected by the purging medium , the same gases can be used for pursing instead of inert gases.
Type 3(Double distance piece)
In addiion to the basic configuration of Type 2 , the process gas leakage is recovered and vented back into suction.
Type 4(Double distance piece)
In case of high back pressure on the distance piece , integral pressure resistance packing case consisting of cylinder pressure packings and intermediate partition packings is provided.
Gas leakage from intermediate part between both packings can be vented outside of the distance piece.
Integrated double distance piece without intermediate partition wall can be purged by inert gases.
Type 5(Double distance piece)
In addiion to the basic configuration of Type 2 , wedge type packing rings are added to both cylinder pressure packings and intermediate partition packings to improve sealing performance utillzing the pressure of buffer gas such as nitrogen.
Small amount of gas leakage into the distance piece is vented to atmosphere.