Improvements in Steam Fire Pumps.

Improvements in Steam Fire Pumps.

Under the above title John R. Freeman, inspector of the Boston Manufacturers Mutual Insurance Co., gives to The Standard the following interesting treatise upon fire pumps:

Fire pumps at the factories we insure are so very frequently found incapable of starting promptly when tried for our inspectors, particularly at the spring inspection, and are in so very many cases* found to be incapable of delivering anywhere near their alleged or rated capacity without violent “ hammering ” as to make it plainly evident that some decided improvement is necessary at the average risk, in one or all three of the following particulars :

The construction of the pump,

The erection and fitting up of the pump,

The care of the pump.

Steam fire pumps are ordinarily sold, rated and expected to run at double the speed of a pump for boiler feeding or any ordinary water supply.

Steam fire pumps do not ordinarily receive such care or attention as a steam engine or other machine on which the product of the mill depends, but after weeks or months of disuse, may be called on to start instantly; therefore a steam fire pump should be built better and more rust-proof than the ordinary

These specifications are based on tests of a great number of pumps new and old, and of all leading makes.

The Deane Pump Co., Henry R. Worthington, and the Knowles & Blake Pump Works are now prepared to furnish pumps built in full accordance with these specifications.

The price is not much more than for the ordinary trade pump when allowance is made for the brass plungers and rods, the pressure gauges, relief valve, suction chamber and priming pipes which heretofore have formed expensive extras, but now are included in the one price, that there may be no excuse for their omission.

BRIEF OF THE PROPOSED STANDARD FIRE PUMP SPECIFICATIONS OF THE ASSOCIATED FACTORY MUTUAL INSURANCE COS.. prepared by John R. Freeman, Hydraulic Engineer, in consultation with Charles C. Worthington, Charles P. Deane and other leading Pump Builders.

  1. Fire pumps must be of the Duplex type, and for all ordinary situations the inside plunger pattern is preferred to the piston pattern.
  2. Fire pumps must be brass fitted throughout, brass plungers, brass fitted piston rods, stuffing boxes, etc.
  3. To gain in simplicity only five stock sizes will be regularly recognized, viz.:

The 1 1-8 smooth nozzle is the standard fire stream.

One stream or 320 gallon pump, piston four to one, commercial size

{ 12 x 6 x 10

or

{ 12 x 6 x 12

Note.—So small a pump as this is acceptable only for very small mills or as a boiler feed pump giving auxiliary fire protection,

Two stream or 500 gallon pump, piston four to one, commercial size,

{ 16 x 8 x 10

or

14 x 7 x 12

Three stream or 750 gallon pump, piston 4 to i, commercial size,

{ 18 1/2 x 9 1/4 X10 or

{ 18 X 9 X 12

Note.—The two sixes last named arc those most commonly called for.

Three stream or 750 gallon pump, piston 3 to 1, commercial size,

{ 16 x 9 1/4 x 10

or

{ 16 x 9 X 12

Four stream or 1000 gallon pump, piston 3 to 1, commercial

{ 18 1/2 X 10 1/2 X10 or

18 X 10 X 12

Note.—The last two pumps with steam cylinder relatively smaller, are acceptable only when boiler pressure is over 75 pounds, and steam kepi up to 50 pounds at night.

Moreover, a very conspicuous enamelled plate stating : ” For fire purposes; never let steam get below 50 pounds,” is to form a part of every such “3 to 1 ” pump.

  1. A “ capacity plate ” is to form a conspicuous part of each fire pump, and must state rated gallons per minute, number of 1 1/8-mch fire streams, and greatest proper number of strokes per minute.
  2. In rating capacity, 75 revolutions per minute will be taken as proper speed for pumps of 10-inch stroke, and 70 revolutions for 12-inch stroke; moreover 10 per cent is to be deducted for loss of action.
  3. Pump must be designed, built and warranted to stand, closing water outlets while steam valve is wide open and steam at 100 pounds, without giving signs of yielding at joints or elsewhere.
  4. Pump must be designed, built and warranted to stand instantly turning a full head of steam on to a cold pump.
  5. The net suction valve port area at each end of each plunger must be : Fifty per cent of plunger area for pumps of 10-inch stroke, 60 per cent of plunger area for pumps of 12-inch stroke, and for longer strokes, valve area must increase in same proportion as stroke. (Force valves may, if desired, give only 2/3 the net area of suction valves.)
  6. Valve springs to be cylindrical, not conical, and properly held and guided, and with valve stems safe against unduly interfering with rise of valve.
  7. Valve scats to be firmly screwed into valve deck, or if forced in on tn|>or without screwing, then projecting lower edge is to be expanded or “ rivet ted ” back securely.
  8. Cushion valves (so-called) on a pump for fire purposes arc a needless complication not regarded with favor.
  9. A permanent length of stroke index is to be attached to each pump.
  10. Least area of each steam passage from chest to cylinder to be not less than 1/2 per cent of piston area.
  11. Flanges and connections for pipes are to be in all cases JUS large as given below. (Which is greater in most cases than heretofore customary.)
Diagrams illustrating the amount of Tradiness of Two Mccurial Thermometers under different rates of rise of Temperature.
  1. A suction air chamber is to form an integral part of every fire pump. For pumps supplied under a head, an open standpipe of same size as suction pipe is preferable to a closed suetion chamber. The capacity of the suction and pressure air chambers atiove top of outlet pipe is to he as follows :
  1. One five-inch, Duplex-spring, water-pressure gauge is to he furnished with and attached to pump; also one five-inch, Duplex-spring, steam pressure gauge.
  2. A relief valve of size given below is to he furnished with each pump (until further tests); the following will he assumed as proper sizes :

For 320 gallon pump a 2)& inch Ashton (or equivalent).

500 “ 3

  1. Drain valves are to be provided and independent brass priming pipes are to he regularly provided for all fire pumps not taking suction under a head.
  2. Two and one-half inch hose valves (I for the 320 gallon,
  3. 2 for 500, 3 for the 750, and 4 for the 1000 gallon pump) are to be attached to pump under the air chamber.
  4. A suitable safety draining attachment or steam trap is to he attached to steam supply pipe near the valve chest.

All the attachments enumerated above are to be considered not as extras, but as forming an integral part of the pump, and be included in its price.

Out of 6o pumps tested by CHIC inspector in his tour of a single manufacturing district, much less than half were found to start up in thoroughly first-class condition.

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