The Fisher Pump Governor.
A display that attracted many water-works men and engineers was the Fisher patent steam pump governor in Machinery hall. The governor is decidedly simple in principle and involves a valve in the main shell which is a double one. the upper disk being the largest, so that there is always an upward pressure on the valve stem. The upper wheel on the valve stem in yoke is simply for a lock nut; the lower one is fastened in place by a small lock nut below it, and by turning this wheel to the right the valve stem is screwed up into the bottom of the piston rod, which raises the valve and admits the steam to the steam chest of the pump. Above the yoke there is a brass cylinder in which is a piston with an ordinary cup leather packing, which piston rests upon a steel coil spring. At top of pipe work over governor is a small globe valve, and from this point a one-quarter inch pipe is taken to and connected with the discharge pipe from the pump, which brings the water pressure from the pipes or mains on to the top of piston in cylinder. Now, if the valve is raised in manner as explained above until the pump has brought the pressure in pipes or mains to the point desired, and the upper wheel or disk in yoke is then set up tight—as a lock nut—against the bottom end of piston rod, the governor will hold the pressure uniformat point set, until changed by the engineer, which is as readily done as by a throttle. The small angle valve is simply for a relief valve, to relieve the pressure between piston head and globe valve above, when globe valve is closed. The small down pipe is to carry off any drip or waste. The whole device is intended to be placed in steam pipe between steam chest and throttle valve, and as close to steam chest as possible.
The simplicity of this device is apparent at a glance. When the water pressure falls below the point set, by the opening of a valve or hydrant or an automatic sprinkler head, or in any way, the pressure being lesson the piston, the steam raises the valve, gradually increases the speed of the pump and maintains the pressure at point desired, and when the water is not being used the increased pressure on piston gradually forces the valve to its seat again, which slows up and finally stops the pump until pressure falls again. It gives a more perfect regulation than it is possible to get by constant care of the throttle, and there can be no over pressure and no damage. It is very sensitive, yet positive, in its action, and automatically controls the pump at all times.
These governors are now made in sixteen sizes, the smaller sizes with screwed ends. They are largely used on water-works pumps, fire pumps, paper mills, etc. Hundreds of them are now in use on duplex pumps running hydraulic elevators, with pressure tank or direct pressure systems. This device is fully protected by letters patent, and is manufactured by the Fisher Governor Company of Marshalltown, la., from whom all further information can be obtained.