Downstream restriction

A protected-side restricdon, snch as a valve, can severely reduce a flame arrester s capabilides by magnilying reflected initial pressure on the arrester element. In snch a sitnadon, a downstream restriction should be included in the test protocol (see Chapter 6). 

Downstream restriction. At the maximum obtainable flow, check the feed of head (as described previously) on the pump curve. If the pump is putting up the head indicated on the curve, do not pull the pump. Ask the instrument mechanic to check the control valve on the discharge line. Perhaps it is not opening all the way or the downstream pressure requirement has increased due to a lunch bucket lodged in an exchanger inlet. 

When fluid flows past objects or through orifices or similar restrictions, vortices may periodically be shed downstream. Objects such as smokestacks, chemical-processing columns, suspended pipehnes, and electrical transmission lines can be sul ected to damaging vibrations and forces due to the vortices, especially if the shedding frequency is close to a natural vibration frequency of the objecl. The shedding can also produce sound. See Krzywoblocki (Appl. Mech. Rev., 6, 39 397 [1953]) and Marris (J. Basic Eng., 86, 185-196 [1964]). 

Gas pressurized Monitor tank level and provide interlock for feed feed shut-off overpressurizes, alternate fluid delivery system (e.g., pump) centrifuge system when feed vessel delivery gas pressure to maximum safe empties working pressure of downstream system (e.g., pressure regulation) Restrict feed flow rate to be consistent with vent capacity Ensure adequate vent capacity for maximum possible gas flow ... 

This condition cannot be corrected on pumps with an enclosed impeller. You need to relax the restricted discharge flow on the pump. The problem could be a clogged downstream filter, a closed discharge valve, an over-pressurized header (back-pressurizing the pump), or a... 

If the pressure Pj downstream of the restriction is less than the critical flow pressure, then the maximum obtainable flow which occurs at critical velocity is a function of P, and P but is unaffected by Pj. If Pj is greater than P , however, then the flow is termed "subcritical," and the rate is a function of P, and Pj. There are thus two equations for sizing PR valves in vapor service, depending on whether the flow is critical or subcritical. 

Equipment downstream of liquid outlet(s) can safely handle maximum gas rates that can be discharged through the liquid outlet(s), and vessel does not have an immersed heating element subject to excess temperature. Restrictions in the discharge line(s) may be used to limit the gas flow rate. 

The detonation flame arrester mnst be able to arrest ten deflagrations with and withont a pipe restriction downstream of the flame arrester and five nnrestricted stable and overdriven detonations. The UL standard states, after tests determine the maximnm nnsta-ble (overdriven) detonation, the arrester is to be snbjected to fonr additional nnstable detonations with the length of pipe that resnlted in the maximnm nnstable (overdriven) detonation. The arrester is also to be snbjected to five stable detonations. ... 

When the downstream pressure is less than (or below) the critical or choked pressure, the velocity and fluid flow rate at a restriction or throat wall not/cannot be increased by lowering the downstream pressure further, and the fluid velocity at the restriction or throat is the velocity of sound at the conditions [29]. 

Contact with the shoppers was restricted to field phase management study personnel, for two reasons. First, clearly defined lines of communication had to be maintained. Second, in order to ensure that the identity of the stores remained blind (i.e., unknown to everyone downstream from sample collection), in compliance with one of the design criteria, communication with the shoppers had to be restricted. Overall, limiting contact with shoppers to one entity and using modern technology, such as facsimiles and e-mail to facilitate and document communications between shoppers and the collection coordinator, were essential factors in the successful conduct of the sampling phase of the study. 

A similar strategy was used to create plasmid pCP47. The insertion of a 10-His-tag was realized by cloning the tag at the end of the psbB gene via the restriction-sites BarnHI and EcoRV (see Fig. 2). In case of plasmid pCP47His, the selection-marker CmR was located downstream ofpsbB. 

Is flow capacity restricted on upstream or downstream side ... 

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