Pressure on a packing gland of a water lubricated pump should be ___ than the pump discharge pressure.

• A. Lesser
• B. Not Related
• C. Equal
• D. Greater

Answer: (D)

In a water-lubricated packing, the packing around the shaft is kept lubricated and cooled by water fed into the packing chamber. Keeping the gland pressure higher than the pump discharge pressure creates a back pressure that prevents the pumped liquid from leaking outward along the packing. Any leakage tends to be carried into the gland’s water system rather than escaping to the atmosphere, because fluid flows from higher to lower pressure. If the gland pressure were not higher, the discharge pressure inside the pump could push fluid past the packing and leak out. So the gland pressure should be greater than the discharge pressure.