Pressure-controlling device

Fig. 1. A trough for deposition of monolayers on soHd substrates A, bath B, a moving barrier C, a motor D, a pressure-control device E, a surface pressure balance F, a motor with a gearbox that lowers and raises the substrate and G, a soHd substrate. The film material (S) has a hydrophobic tail and...

Each input source is protected by a PSL, and there are no pressure control devices or restrictions between the PSL(s) and the vessel. 

Example of a pressure control device for a steam engine. 

Sugden s method appears to combine the advantages of speed, simplicity, and accuracy to a greater extent than any other method and it has the advantage that a fresh liquid surface is formed for each determination, so that there is little risk of contamination. Theoretically the bubbles must be formed slowly, but in practice no change in the pressure reading occurs if the rate is reduced below about two per second, with pure liquids. If a simple pressure controlling device is used to blow the liquids over,... 

The pressure control and monitoring devices used should be calibrated and qualified. Compliance with specifications should be regularly verified and the results recorded. Pressure control devices should be linked to an alarm system set according to the levels determined by a risk analysis,... 

Air supply subsystem, including blower or compressor, air humidification, heat exchanger and pressure control devices to deliver process air at the required mass flow, pressure temperature and humidity to the fuel cell stack. Separation of water from the used air stream and, in some cases, an expander add more complexity to the air supply subsystem ... 

LOW-SIDE PRESSURE CONTROL - Device used to keep low side evaporating pressure from dropping below certain pressure. 

Gas Pressure Control Device. The gas pressure over the cryogenic liquid in the measuring vessel and guard vessel is subject to atmospheric pressure changes. These changes can lead directly to boil-off measurement errors. Calculations show that the pressure above the cryogenic liquid should be controlled within 0.1 torr however, the atmospheric pressure variation may extend over several torrs. 

Monitoring devices pressure gauge, backflow monitoring device, standstill and synchronizing device, overload safety device, pressure control device, temperature sensor, counters, speed monitoring devices, service hour counter... 

Improvement in the control of coke oven gas discharge evolved through the availability of better gas exhausters, coupled with more sophisticated pressure control devices to maintain uniform pressure at the ovens. 

Zone 1 consists of the eleven SCBs located within the Zone 2A canyon and the associated ventilation ducting. These SCBs will have the highest contamination levels, and are maintained at a negative pressure relative to Zone 2A to control the migration of contaminants. Airflow is drawn from Zone 2A into each SCB from the conveyor duct through a pressure control device and then exhausted through the Zone 1 ventilation ducting. The conveyer volume draws filtered air from Zone 2A at the north end of the duct. When the conveyer hatch cover is opened to move materials into or out of the SCB, the pressure differential between the SCB and the conveyer volume will approach zero, however, the airflow into the SCB, which acts to prevent... 

A schematic diagram of the apparatus is shown in Fig. 5.14. The pressure system varies in complexity, but the automatic pressure controlling devices available commercially are easily adapted to computer control. Although the capillary rise and maximum bubble pressure electrometers are absolute instruments, they are usually calibrated with a solution of known properties. This avoids the accurate measurement of the radius of the capillary bore. 

Positive displacement pumps are not supposed to be throttled or regulated on the discharge side. After the line has been walked and every valve has been checked, the pump can be started. Suction and pressure gauges should be carefully monitored, and flow rates tracked. Flow control loops are typically not used with PD pumps unless a series of relief valves and pressure control devices is used. A simple calculation should be made on how fast the tank will fill and how fast the suction tank will empty. Careful monitoring of liquid levels is important. Samples are frequently caught on the product lines and sent to the lab for quality checks. Some PD pumps are designed to be run liquid full at all times, whereas others can be run empty for short periods of time. 

Figure 3.23. Schematics of an instrument for thermogravimetric analysis of substances including volatile components (TG-Analysis). The instrument is equipped with a gas dosing system and pressure control devices. Rubotherm GmbH.

In Figure 3.23 the basic flow diagram of an instrument for thermo-gravimetric measurements with an automated gas dosing system and pressure control device is sketched. Application oriented details and hints for the measurement procedure are given in [3.5, 3.6]. 

Consideration of Flow Devices—Positive Attributes of Modern Electronic Pressure Control Devices... 

FIGURE 10.13 To ensure effective operation, maintain at least a 10-15-psig pressure differential across all flow and pressure-controlling devices [reprinted with permission of Supelco, Bellefonte, PA 16823 (USA)]. 

In hydraulic circuits, the return or common ports should be connected to a return line that direcdy connects the valve to the reservoir tank. This return line should not need a pressure-control device, but should have a check valve to prevent reverse flow of the hydraulic fluid. 

Schonhofer B, Sonnegom M, Haidl P, et al. Comparison of two different modes for noninvasive mechanical ventilation in chronic respiratory failure volume versus pressure controlled device. Eur Respir J 1997 10 184-191. 

Study on Pressure Control Device to Improve Foaming Uniformity for the Injection Molding Microcellular Foaming Process... 

The size and uniformity of the cells were very drfficnlt to control in the microcellular foaming process. We nsed the pressure control device to postpone the pressnre drops dniing the molding procedure, leading to a shorter growth time of bubbles, which resulted in a smaller and more nniform cell stracture. The cavity pressnre cnrve withont the nse of pressure control is shown in Fig. 3. The cavity pressure curve using the horizontal pressnre control device is shown in Fig. 4. The inflnence on cell size and snrface roughness is discussed as follows ... 

The mold using the vertical pressure control device... 

The injection pressure was lOOObar. The results are shown at Table 2. For the parts injected without the pressure control device, the flow sink was irregular and had a disorder distribution (Fig 5a). For the parts injected using the vertical pressure control device, the flow sink was thinner and less obvious than the parts in case 1 (Fig 5b). There were no bubbles at the surface because the controlled pressure was higher than the pressure inside the bubbles. Therefore the skin was transparent without bubbles, and possessed a reflecting ability. Surface roughness improved from Ra 26.47 to Ra4.03. 

The mold using the horizontal pressure control device and hot nozzle system ... 

Injected with a higher molding temperature and a pressure control device, the skin thickness was... 

Injected with the pressure control device, the surface flow sink was directional and attenuated, which improved the surface roughness. The optical reflection effect was 10% more than the traditional... 

Injected using the pressure control device and hot nozzle system hardly improved the surface roughness, but the optical reflection effect was 30 % more than using the traditional process and is very close to the optical specification of the backlight module. 

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