Strainer

Sizing to include potential startup loads leads to oversizing in thermodynamic traps. A thermodynamic trap will handle a great deal more cold condensate than hot condensate and if a still greater rate is desired, the line can be manually blown down. For applications other than steam tracing, careful consideration should be given before introducing any startup allowance, especially if the addition requires an increase in trap size. 

For steam tracing applications, a flow rate of 100 pounds per hour gives the best balance between trap sizing and traced length of pipe. The allowable lengths at various temperatures stays within the realm of possibility while the unavoidable short runs do not cause the flow rate to fall into the trap s inefficient range. 

On this basis, the selection of a group of steam traps to handle all steam tracing situations is possible. Actually this consists of a 3/8-inch nominal size trap but many steam trap manufacturers rate their traps by orifice size rather than by connection size. Suitable traps should have 150 psig steam condensate capacities from 350 to 600 pounds per hour at saturation temperature, and from 550 to 850 pounds per hour at 30°F below saturation temperature. Using 15 psig steam, the condensate capacity should range between 135 and 250 pounds per hour at saturation temperature and from 225 to 400 pounds per hour at 30°F below saturation temperature. 

Field and laboratory tests have shown that the nominal 3/8-inch size trap will operate efficiently below 20 pounds per hour and has enough capacity to give safety factors of 2 or more, depending on the trap, based on a 100 pounds per hour normal load. 

Low Loads and Cycling. The trap should be able to handle loads down to a very small percent of its rating which should be in the realm of 2 to 3% at operating temperature. Cycling, or condensate blowing, should occur at a rate of 3-to4 cyc./min. rate, with a blowing time of 5 to ten seconds. With proper operation, the trap will not allow condensate buildup in the tracer and will blow down completely each time. This, of course, is a bare trap insulation should not be applied to a thermodynamic steam trap. 

For a Handbook devoted to the removal of suspended contaminants, there is no better way to start than with the strainer, whose function is entirely that of protecting downstream items of equipment, or downstream processes, from the impact of impurities that may block narrow passageways or abrade sensitive surfaces. 

Strainers offer a simple method for the protection of pipeline systems, by removing debris such as dirt, swarf, weld sputter, scale and so on. They are simple coarse filters using perforated plate or wire mesh as the filter medium. Strainers fall broadly into two categories temporary strainers and permanent strainers. 

It is true that many types of filter could act as a strainer but it is rare that the straining function (unless at very low cut-points) needs anything more complicated or expensive than the simple units described here. 

Tanporary strainers are intended for short periods of application, such as being fitted during the run-in period of a new system, or when restarting a pipeline system after shut-down and maintenance. They are intended to remove coarse debris particles present in the systan. After a suitable period of use, they are removed (and can be cleaned and stored for future use). 

Where fitting such strainers is difficult or impractical on a particular system, other types of temporary strainers are available to match a blind T-junction fitting, into which they can readily be fitted and removed. These strainers are often of a trough shape, and have become referred to as bathtub strainers. 

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To lessen the risk of pumping sludges or slurries into a unit, the practice is to leave a safety margin of 50 cm (heel) below the outlet nozzle or install a strainer on the pump suction line. The deposits accumulate with time and the tanks are periodically emptied and cleaned. 

Surface Filters. In surface filters (Fig. 2), the goal is to achieve separation on the upstream side of a relatively thin filter medium. The particles to be separated must be larger than the pores in the medium, ie, in strainers, membrane filters, etc, or the particles must approach the pores in large numbers and bridge over the pores, as in cake filters. 

Sediment. The sediment test consists of filtering a definite quantity of milk through a white cotton sediment test disk and observing the character and amount of residue. Efficient use of single-service strainers on dairy farms has reduced the use of sediment tests on milk as deflvered to receiving plants. Although the presence of sediment in milk indicates unsanitary production or handling, its absence does not prove that sanitary conditions always existed. 

Fig. 3. Brewing (1 = mash turn 2 = mash kettle 3 = lauter tun 4 = wort kettle 5 = hop strainer 6 = wort tank 7 = wort separator and,...

Treatment of the Wort. The hot wort produced in the brewhouse cannot be transferred directly to the fermenting room. If natural hops are used they must be separated by a hop strainer as shown in Figure 8. During boiling, protein—tannin complexes are precipitated in the form of warm sludge. 

Fig. 8. Wort filtering in a whirlpool (1 = wort kettle 2 = hop strainer 3 = whirlpool tank and, 4 = wort cooler).

Whole egg changes consistency during freezing. When thawed, it has a watery, separated appearance. After passing through a strainer or mixing in a vat or container, it appears to be uniform and smooth. 

In the absence of more direc tly applicable data, the flexibility factor k and stress-intensification factor i shown in Table 10-54 may be used in flexibihty calculations in Eq. (10-101). For piping components or attachments (such as valves, strainers, anchor rings, and bands) not covered in the table, suitable stress-intensification factors may be assumed by comparison of their significant geometry with that of the components shown. 

Figure 6.15 A main mill water-strainer basket caked with clams.

Inadequate piping, sharp elbows, restrietions, conneetions, filters and strainers in the suetion. 

C liiiiigc filters and strainers with more frequeney. 

It is neeessary to understand the TDH and it s eomponents in order to make eorreet deeisions when parts of the system are changed, replaced, or modified (valves, heat exchangers, elbows, pipe diameter, probes, filters, strainers, ete.) It s neces.sary to know these TDH values at the moment of specifying the new pump, or to analyze a problem with an existing pump. In order to have proper pump operation with low maintenance over the long haul, the BF P of the pump must be approximately equal to the TDH of the system. 

In the long term, filters and strainers become clogged this is their purpose. Minerals and scale start forming on the internal pipe walls and this reduces the interior diameters on the pipe. A 4 inch pipe will eventually become a 3.5 inch pipe. This moves the pump on its curve beeause as the pipe diameter reduces, the velocity must increase to maintain flow through a smaller orifice. The Hf and Hv increase by the square of the velocity increase. 

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). 

Boiling water (ca. 150 ml) is poured over a inblc-spoonful of lea, covered and allowed to draw for 10-15 min., and then pa.ssed through a tea strainer. If not otherwise prescribed, a cup of the freshly prepared tea is drunk 2-3 times a day and before going to hed. 

Stomach and intestinal ulcers. 8.3 Side effects Occasionally, headaches may be caused in people who are sensitive to bitter substances. 8 4 Dosage and manner of use Boiling water (ca. 150 ml) is poured over two tea-spoonfuls of the Lea, covered and allowed to draw for 5 10 min, and then passed through a tea strainer. If not otherwise pre.scribed, a cup of the fresh and 8.2 Dosage and manner of use Boiling water fca. 150 ml) is poured over a table-spoonful of the tea, covered and allowed to draw for ca. 10 min., and then passed through a tea strainer. 11 not otherwise prescribed, a cup of the freshly prepared tea is drunk warm several times a day between meals. 8.3 Note Store protected from light and moisture. 

The reservoir may be either pressurized or atmospherie. It must have suffieient eapaeity to eontain all oil during drain-baek or shutdown. It must be equipped with an oil level indieator, a low-level alarm switeh, safety relief valve, a pump for oil makeup during operation, drain valve, heater, mist eliminator, strainers, and required valves. Expander reservoirs must be designed and eonstrueted in aeeordanee with applieable ASME eodes. Reservoir retention time is typieally between 5-18 min depending on turboexpander size and manufaeturer s sizing eriteria. This is an area where the owner/purehaser should ask for the manufaeturer s assistanee. 

Oil Expressed as oil or chloroform extractable matter, ppmw Scale, sludge and foaming in boilers impedes heat exchange undesirable In most processes Baffle separators, strainers, coagulation and filtration, diatomaceous earth filtration... 

Defective pressure gauge. 10. Plugged oil sump strainer. 11. Defective oil relief valve. PACKING OVERHEATING 1. Lubrication failure. 2. Improper lube oil and/or insufficient lube rate. 3. Insufficient cooling. 

Clogged oil strainers or filters. vibration, disconnect 6. Dry coupling (if continuously... 

Temporary strainers and blinds installed Provisions for sampling... 

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