Suction bell

The suction bell reduces entrance losses and helps to prevent vortices. If you use a basket strainer, the screen area should be four times the area of the entrance pipe. Avoid tight mesh. screens because they clog quickly (Figure 17-8). 

A suction bell on the inlet of a vertical pump (or the inlet pipe of the suction side of a horizontal pump) is not necessary as far as pump or sump operation is concerned. If a bell is omitted, the entrance losses due to flow will be higher ith only a straight pipe, and this must be considered in pump operation. An economic comparison vsill help decide the value of the bell. Strainers should not be placed on suction bells unless this is the only arrangement. Inlet water should be screened with trash racks, bars and screens to keep the sump free of debris. 

The paper discusses suction-intake design, suction-bell submergence, air-entrainment potential, and net positive suction head of cooling towers. Guidelines on possible problems and ways to assure reliable operation of cooling towers are given. 

Especially critical in fire pump installations from open bodies of water is the activity of underwater diver operations in close proximity of the underwater fire pump suction bell or opening. Underwater diving operations routinely occur at the structural support (i.e., the jacket) for offshore installations for corrosion monitoring, modifications, inspections, etc. The high water current at the intake to the submerged pump poses a safety hazard to divers as they may be pulled into this intake. During the operation of the ill fated Piper Alpha platform it was common practice to switch the fire pump to manual startup mode (requiring an individual... 

Matheson, Coleman, and Bell mabsolute ethanol contEflining 0.02% glacial acetic acid (Note 6) and filtered by suction. The ffiltrate was cooled, and the white plates of mercuric acetate were collected by suction filtration and stored under vacuum. 

Vertical glass(seldom plastic or metal) tube 200-250mm long and ca 35mm in diam, provided at the bottom with a coarse porous porcelain disc or a loose wad of glass wool. This part of the tube is connected thru a std taper joint to a thistle-shaped funnel which is inserted(thru a hole in rubber stopper) into the neck of a bell jar suction filtrate assembly in the manner to... 

The bell is then placed in a beaker a of about 200 c.c. capacity so that the covered mouth of the bell almost touches the bottom of the beaker. Into the latter a little of the tanning solution is poured and when this has all been sucked up by the hide powder (usually in about an hour), the beaker is filled with the tanning solution and the siphon filled with the liquid by suction at its free end. The liquid flows slowly from the siphon so that the efflux of about 100 c.c. requires 1-5-2 hours. 

Bell, S. P., Nyland, L., and Tischler, M. D. (2000). Alterations in the determinants of diastolic suction during pacing tachycardia. Circ. Res. 87, 235-240. 

Lead tetraacetate. Pb(OCOCH.i)4. Mol. wt. 443.39. Suppliers Arapahoe Matheson, Coleman and Bell G. Frederick Smith Co. Commercial material contains 96-97% of small crystals of lead tetraacetate moistened with acetic acid and a trace of acetic anhydride to prevent hydrolysis. The paste is best stored at 5°. To obtain dry material, scrape a batch of paste onto a suction funnel, wash it with acetic acid to form an even cake, suck the cake thoroughly, and let it dry at room temperature in a dark place in the hood. Usually the presence of acetic acid in the reaction mixture is not objectionable and in this case the paste can be used as received after iodimetric analysis. A weighed sample of about 0.5 g. is dissolved in 5 ml. of acetic acid by gentle warming, and a solution of 12 g. of anhydrous sodium acetate and I g. of potassium iodide in 100 ml. of water is added. After swirling for several minutes the flask wall is rinsed with water, and the liberated iodine is titrated with 0.1 N sodium thiosulfate to a starch end point. 

In order to obtain the degree of vacuum required, the manufacture of the de-airing bell must be very accurately accomplished and it must be provided with suitable seals and scrapers to prevent soiling. Moreover the suction point in the receiver must be suitably protected against penetrahon of contaminating material. 

Fig. 3.22. Single stack cover furnace with four-coii ioad. Recuperator with suction Venturi is the size of a person. Circulating fan in base drives prepared atmosphere through coiied strip under alloy cover. Bell-type furnace is lowered over a loaded inner cover. One or two circles of high-velocity, tangentially fired burners fire between the inner bell cover and the and outer bell furnace.

NPSH estimate in the pump suction was in fair agreement with the water test data and indicated that a suction specific speed of 39,300 was achieved before cavitation. Examination of the pumps after the cavitation had occurred revealed that there was no physical damage. It is interesting to note that if the suction line from the tank were increased to 16 in. and an efficient bell mouthed inlet were used in the tank, the suction line losses would be reduced sufficiently to permit operation of the system with the tank ullage vented to atmospheric pressure. 

Net Positive Suction Head was also measured directly using the vapor bulb versus static head method devised by NBS, This is shown to the left of the inlet bell. 

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