Suction detection

For gaseous contents, visual monitoring is unlikely to be satisfactory and a suction detection or pressurization method with a readily identifiable gas (or volatile liquid providing a gaseous presence) may be used. Again, a careful visual inspection... 

Passive infrared, visible light O Suction detection... 

Whenever possible, external relief valves should be furnished. On the larger systems, this is mandatory. Internal relief valves will lead to pre mature pump failure if allowed to operate open for more than a few minutes, since the hot oil is returned directly to the suction. An upset period, the time when a pump may open the relief, is probably not the time when an operator would detect the open valve and shut the pump down to r< t the valve. 

The leak could have been stopped as soon as it was detected if an emergency isolation valve (Section 7.2.1) had been fitted in the pump suction line. On the rebuilt plant such valves were fitted on the pump suction lines, more combustible gas detectors and more extensive insulation were installed, plastic pump bodies were replaced by metal ones, and spillages were directed to collection pits. The plant was built in 1972, when these features were not common practice many improvements had been made since then, but they did not go far enough. Most of those made after the fire could have been made beforehand. 

Expansion valves for such circuits embody a mechanism which will detect the superheat of this gas leaving the evaporator (Figure 8.5). Refrigerant boils in the evaporator at Tg and p, until it is all vapour, and then superheats to a condition Tj, p, at which it passes to the suction line. A separate container of the same refrigerant at temperature Tj would have a pressure and the difference p is a signal directly related to the amount of superheat. 

Since the oil pump inlet is at sump (suction) pressure, a pressure gauge on the pump discharge will indicate the total pressure at that point above atmospheric, i.e. suction (gauge) plus pump head. Any detection element for true oil pump pressure must sense both suction and pump outlet pressures and transduce the difference. Oil safety cut-outs have pipe connections to both sides of the oil pump and two internal bellows are opposed to measure the difference. 

Percent solid settled In tests where adsorption and flocculation were determined simultaneously, the 200 ml sample was allowed to settle for 30 seconds and then 100 ml of the supernatant was removed using a suction device and after centrifugation analyzed for residual polymer concentration. The minimum level of detection was at 0.5 to 1 ppm and the reproducibility of the adsorption measurements was 2-3%. The settled 100 ml portion was analyzed for solid content. Flocculation due to polymer addition is measured by noting % solid settled as a function of polymer concentration. 

Automatic refilling using an automatic float valve should be provided. A maximum refill time of 8-hours is recommended (NFPA 22). Low-level alarms to protect the pumping unit should be provided. Suction pits associated with reservoirs should be monitored by level alarms to detect suction screen plugging. 

An example of a causal factor chart for a relatively simple incident is shown in Figure 9-8. In this example, there are two redundant pumps, one of which is required to supply feed to a reactor downstream. The operator is requested to change-over operation from Pump A, which is running, to Pump B, which was previously shutdown. Instead of opening Pump B suction valve, the operator opens the wrong valve, causing the Reactor to trip on low flow detection. 

Remove both the Suba-Seal and polythene cap and place the filter tube in the rubber cone adapter (42 x 27 mm) used with the adapter funnel attached to the Buchner flask, or other suitable device. Wash any particles from the polythene cap into the filter tube, apply just sufficient suction to remove the gamanase-cellulase solution, then wash the residual undigested fibre with hot distilled water (approximately 80°C). Finally wash well with acetone, leave to air dry in a fume cupboard, and when no smell of acetone can be detected, dry in an oven overnight at 100°C ( 2°C). Cool in a desiccator and weigh the filter tube plus residue. 

He prepared the SPE by first wetting it with 2 mL of methanol and then with 2 mL of water. Next, the SPE was attached below a particulate filter in a line leading to a 1-L suction flask (Fig. 12.1a). The inlet of the SFE was fitted with a tube dipped into a 1-L flask of the runoff water containing our compound, XX, at 5 parts per trillion. (He was unable to detect this level of compound by direct injection into an HPLC system.)... 

As each particle can be detected as spot of light, therefore, slit ultramicroscope helps to determine the number of particles in a definite volume. The great value of the slit consists in the ability by its use to suction off a portion of the fluid which is being examined. Zsigmondy (1912) devised an immersion ultramicroscope, which was used with strongly coloured liquids. In it, illumination objective and microscope objective are brought as close as possible, and the liquid to be investigated can be used as a drop between the two lenses. 

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