What is the purpose of backseating a manual valve in an operating system?

The purpose of backseating a manual valve is to isolate system pressure from the packing stuffing box, thus minimizing packing leakage. When a valve is backseated, the valve's stem is pulled back, which prevents the pressure in the system from being applied to the packing material around the valve stem. This is crucial because when pressure is applied, it can cause packing to leak, leading to potential system inefficiency and safety hazards. By backseating the valve, operators ensure that the packing is no longer under pressure, which protects it and helps maintain a leak-free operation.

The other options suggest benefits such as reducing leak rates or improving flow rates or maintenance ease, but they do not specifically address the critical action of isolating the packing from system pressure, which is the primary concern when backseating a valve. Therefore, option C stands out as the most accurate reflection of the primary function of backseating in relation to valve operation and maintenance.