Nash Engineering Co. v. WD CASHIN & CO.

• Citation: 3 F.2d 686
• Decision Date: 21 January 1925
• Docket Number: No. 1891.,1891.
• Parties: NASH ENGINEERING CO. v. W. D. CASHIN & CO. et al.
• Court: U.S. District Court — District of Massachusetts

3 F.2d 686 (1925)

NASH ENGINEERING CO. v. W. D. CASHIN & CO. et al.

No. 1891.

District Court, D. Massachusetts.

January 21, 1925.

Southgate & Southgate, of New York City, for plaintiff.

Fish, Richardson & Neave and J. L. Stackpole, all of Boston, Mass., and Lynn A. Williams, of Chicago, Ill., for defendants.

LOWELL, District Judge.

This is a bill in equity to restrain the infringement of reissued letters patent No. 15,637, granted June 26, 1923, to L. C. Jennings, and assigned to the plaintiff. The patent relates to a so-called vacuum heating system. Such a system depends for its operation on establishing a partial vacuum in the return lines from the radiators in a steam heating system. Its main features have been well known for some years. They comprise a low-pressure boiler as the source of the steam, pipes connecting the boiler with the radiators, and return pipes to bring back the water resulting from the condensation of steam in the radiators. There is a valve or trap at the outlet end of each radiator, which acts automatically to allow the water to flow back.

In this system the circulation of the steam is brought about, not by pumping it through the pipes, as had been done in the older art of steam heating, where high-pressure boilers were used, but by drawing the steam through them. This is done by creating a partial vacuum in the return lines. Before the invention of the patent in suit the vacuum had been produced by the use of air pumps of various kinds in connection with a receiving tank. There were two well-known ways in which this tank could be used. In the first the returns were led directly to the tank, while in the second they were pumped to the tank by a pump called an air pump, which handled the mixture of air and water of which the returns consisted. The volume of water coming back varies greatly with the temperature. On warm days very little water returns, because the steam is not rapidly condensed. On cold days, however, a good deal of water comes back, and is apt to come intermittently, or, as expressed by some of the witnesses, "inslugs." Air gets into the radiators or pipes by leakage from without, as the system is under a vacuum. The air comes back continuously, and must be discharged from the system, because it would be dangerous to let it get into the boiler. An important feature of a pumping apparatus used in connection with a vacuum heating system is that the air pump shall operate continuously, while the water pump shall operate intermittently. None of the devices in use had been very successful. The patentee devised a system which is completely successful and has been generally adopted. He claims to have revolutionized the vacuum steam-heating art. Making due allowances for an inventor's enthusiasm, this claim is fairly supported by the evidence. There is no question in my mind but that the device used by the patentee has been of great benefit to the public.

The plaintiff's apparatus was built up around the Nash pump, as appears by the statement on page 3, line 38, of the patent in suit, that:

"The hydro-turbine pump is described more in detail in patent 1,091,529, granted March 31, 1914."

The specification of that patent, which was granted to L. C. Nash, refers to the invention as follows:

"My invention relates to improvements in air compressors, vacuum pumps, and similar devices. * * *"

The operation of Nash's device may be described as follows:

"A rotor revolves in an elliptical casing partly filled with water. The water approaches and recedes from the hub, and in this manner acts as a liquid piston, displacing the air in the spaces" (called displacement chambers) "between the vanes of the impeller." Marks' Mechanical Engineers' Handbook (2d Ed.) p. 1608. The inlet and outlet ports are situated near the hub of the rotor. "As the water recedes from" these displacement chambers, "it draws in air through the inlet ports. When the water is forced back" into the displacement chambers "by the converging casing, the air is first compressed and then discharged through the outlet ports." Plaintiff's Exhibit 5, Nash Engineering Co. Bulletin.

The Nash pump is not an air pump at all, as that expression is commonly used in denoting a pump which will discharge air mixed with water. It is rather a blower, and is so classed by Marks, p. 1608. Water is not discharged by it. Indeed, its very operation is dependent on water being retained within the casing in which the rotor revolves, to act as a liquid piston (or series of pistons) to suck in and expel the air. Water is not necessary for the operation of the device. The plaintiff's expert, Mr. Livermore, stated that mercury might be used as an operating liquid. The so-called displacement chambers of the apparatus correspond to the cylinders of a reciprocating pump, while the water in each chamber corresponds to the piston.

I am doubtful on the evidence, which is meager on this point, whether the Nash apparatus could be so changed as to operate as an air pump to handle air and water; it is certain that it would not work efficiently.

As a blower the Nash device was not effective, because, as explained by Marks, p. 1608, there was loss of power due to skin friction. Jennings conceived the idea that this device might be used, not as a blower, to force air forward, but like a fan, to exhaust it from the tank to which the returns from the system were conducted. This was a brilliant idea, which Jennings ingeniously carried out to a successful conclusion, and produced an apparatus of great practical utility and commercial value.

Jennings describes his invention as follows:

"This invention relates to a wet vacuum pumping apparatus. The object of the invention is to provide an apparatus in which the air and water are separated, and the air exhausted by means of a pump and delivered into the atmosphere; the water being withdrawn by a separate pump and discharged against any desired pressure." Patent, p. 1, line 9.

"Briefly stated, my apparatus comprises a receiver, into which the returns of air and water are discharged; the water collecting in the bottom and the air in the upper portion of the receiver. A pumping unit is provided, which comprises a centrifugal water pump and a hydro-turbine air pump. The latter is connected to exhaust the air and discharge the same where desired. The water pump is connected to the lower portion of the receiver and withdraws the water from the latter and discharges it where desired." Page 1, line 51.

There are 19 claims in the patent, 7 of which were sued on. These are claims 2, 3, 4, 5, 6, 13, and 19.

They are as follows:

"(2) The combination, with the separating chamber of a vacuum steam-heating system, of a rotary gas pump employing water for its pumping action and having a rotor provided with displacement chambers, said pump being connected and operating to exhaust the gas from the system by the suction and displacement action of the water in said chambers, and a water pump connected and operating to withdraw water of condensation from the separating chamber.

"(3) The combination, with the separating chamber of a vacuum steam-heating system, of a rotary gas pump employing water for its pumping action and having a rotor provided with displacement chambers, said pump being connected and operating to exhaust the gas from the system by the suction and displacement action of the water in said chambers, and to retain all the water in the system, and a water pump connected and operating to circulate the water of condensation back to the boiler.

"(4) The combination, with the separating chamber of a vacuum steam-heating system, of a rotary gas pump employing water for its...