Surge accumulators

What the PED does say in its ESR related to SRVs is that pressure-limit- PED categories ing devices must prevent the maximum allowable pressure being permanently exceeded. The safety valve (SV) should be set at PS (= MAP) or lower, with exception of momentary pressure surge (accumulation) which is 10% of PS in all cases (multiple valves also) and except for fire, this can be higher if proven safe. This is much more general but definitely differs with ASME as described in detail in Section 3.6. 

Woolfolk became concerned over the adequacy of the SRV test facilities, which were commonly used by many commercial SRV test and repair shops and most chemical plants. The typical test stand consisted of a clamp-down table connected to a compressed air cylinder by a 1/4-inch (0.6 cm) tubing. Woolfolk experimented with surge accumulators for testing relief valves, using a substantial volume of air to mimic actual process conditions. 

Rake-Lifting Mechanisms These should be provided when abnormal thickener operation is probable. Abnormal thickener operation or excessive torque may result from insufficient underflow pumping, surges in the solids feed rate, excessive amounts of large particles, sloughing of solids accumulated between the rakes and the bottom of... 

The performance of reciprocating pumps provides for ease of operation and control. Depending upon the type of piston action, the fluid may be subject to pulsations unless accumulator or surge drums are provided. 

The specification and sizing of surge tanks and accumulators is discussed in more detail by Mehra (1979) and Evans (1980). 

Less explored is the role and metabolic fate of 2-AG. It is possible that in many tissues, 2-AG is only an intermediate of a signaling pathway that generates 1,2-diacylglycerol and arachidonic acid, two well-known signaling molecules. In the brain however, 2-AG may have regulatory roles, since it escapes immediate metabolism and accumulates in response to stimuli-generated Ca2+ surges (Stella, 1997). These differences may arise... 

Larger gas capacities can be handled in a horizontal cylinder than in the same diameter vertical cylinder. However, higher gas throughput usually leaves less space for liquid surge and for the accumulation of mud, sand and paraffin. The application of this type separator is very satisfactory for known flowing conditions in a moderately clean well-stream. 

The reaction mixture is pumped away from the reactor with an alkymer transfer pump, through a steam heater and an orifice mixer into the alkymer wash and surge tank. Dilute caustic solution is recirculated from the a.w.s. tank through the orifice mixer. Makeup of caustic is from a dilute caustic storage tank. Spent caustic is intermittently drained off to the sewer. The a.w.s. tank has an internal weir. The caustic solution settles and is removed at the left of the weir the alkymer overflows the weir and is stored in the right-hand portion of the tank until amount sufficient for charging the still has accumulated. 

This is used in the following way in Layer 3 Normally the bit reservoir is kept at somewhat below the maximum number (accumulated deviation). If there is a surge in PE due to the pre-echo control then additional bits taken from the reservoir are used... 

For treating water containing VOCs with separation factors of more than 500, for which concentration polarization is a serious problem, feed-and-bleed systems similar to those described in the chapter on ultrafiltration can be used. For small feed volumes a batch process as illustrated in Figure 9.16 is more suitable. In a batch system, feed solution is accumulated in a surge tank. A portion of this solution is then transferred to the feed tank and circulated at high velocity through the pervaporation modules until the VOC concentration reaches the desired level. At this time, the treated water is removed from the feed tank, the tank is loaded with a new batch of untreated solution, and the cycle is repeated. 

Uchimura N, Aizawa K, Nagae 7 et al. In vivo accumulation of mono-L-aspartyl chlorin e6 in injured arteries after angioplasty. J Japan Soc Laser Surg Med 2000 21(1) 1-8. 

Hayashi J, Saito T, Aizawa K. Change in chemical composition of lipids accumulated in atheromas of rabbits following photodynamic therapy. Lasers Surg Med 1997 21(3) 287-293. 

In the ovary the ovulatory surge of LH increases blood flow [98]. This is accompanied by an increase in vascular permeability in the follicles resulting in oedema which persists through the time of follicle rupture and ovulation. The effect of LH can be mimicked by histamine but not by FSH or serotonin. Leukocytes accumulate in Graafian follicles near the time of ovulation and fibroblasts migrate from the theca layer to the stratum granulosum. 

Tumour necrosis factor-a (TNFa) accumulates in the brain after trauma. This cytokine is known to be an important factor in delayed CNS damage. It was found that, in addition to its anti-NMDA effect, HU-211 causes up to 90% inhibition of the TNFa surge after closed head injury in rats [195], Bacterial and viral infections of the CNS are known to cause secretion of the TNFa as well as interleukin-1 and other cytokines which are involved in the inflammatory process and may cause secondary damage. Such infections may result in high mortality. It was found that rats infected with Streptococcus pneumoniae suffered less cerebral oedema on treatment with a combination of a suitable antibiotic with HU-211 than the antibiotic alone [196],... 

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