Multi-ports

Multi-Port This term refers to any vaWc or manifold of s ah es with more than one inlet or outlet. For throttling control, the three-way body is used for blending (two inlets, one outlet) or as a dh ertor (one inlet, two outlets), A three-way S ah e is most commonly a special globelike body with special trim that allows flow both o cr and under the plug. Two rotaiw s ah es and a pipe tee can also be used. Special three-, four-, and fh e-way ball- ah e designs are used for switching applications. 

The run and regeneration cycle on small to medium-size units is normally governed by a multi-port valve, which is the only moving part required. There have been many cases where this has failed and brine was injected directly into the boiler. A conductivity meter on the make-up line would guard against this. 

Fig. 13 shows an example where data for an irregular struetured multilayer thin-film-filter (TFF) are imported into a waveguide design. A FDTD-simulation earned out in order to check the influence of the internal resonator-like strueture of the TFF onto the waveguide deviee shows a signifieant transversal shift for oblique incidence. This hinders symmetrical multi-port designs, but may be used for specific WDM functionality. ... 

Subroutines within the overall QuickBASIC program monitor and control the communications ports. This configuration overcomes MS-DOS Hmitations and allows simultaneous communications across multiple communications ports. The multi-port access permits future expansion of the system, with other peripherals requiring communications with the control program. 

The compressed, heated air is supplied to the ramburner through the air injection ports. Two types of air-injection ports, forming a so-called multi-port, are shown in Fig. 15.14 the forward port (two ports) and the rear port (two ports). The multi-port is used to distribute the airflow to the ramburner 34% is introduced via the forward port and the remaining 66 % via the rear port. The combustible gas formed by the combustion of the gas-generating pyrolant is injected through the gas injection nozzle and mixed with the air in the ramburner, and the burned gas is expelled form the ramburner exhaust nozzle. The pressures in the gas generator and the ramburner are measured by means of pressure transducers. The temperatures in the gas generator and the ramburner are measured with Pt-Pt/13%Rh thermocouples. 

Fig. 15.21 Ducted rocket with multi-port air-intake.

When the airflow induced from the atmosphere is introduced through the singleport intake, the mixture formed in the forward part of the ramburner is fuel-lean because all the air induced from the single-port air-intake is introduced into the forward part. Thus, an excess-air mixture (fuel-lean mixture) is formed, the temperature of which becomes too low to initiate self-ignition. However, when a multi-port intake is used, the airflow is divided into two separate flows, entering at the forward part and the rear part of the ramburner. At the upstream flow, the air-to-fuel ratio can be made stoichiometric, which allows the mixture to ignite. At the downstream flow, the excess air is mixed with the combustion products and the temperature is lowered to increase the specific impulse. 

Fig. 15.22 Combustion efiflciency of boron particles when two single-port intakes or two multi-port intakes are used.

These nozzles are available as a single-port or multi-port design. Generally, the single port nozzles are adequate up to 100 kg batch, but for larger size batches a multi-port nozzle such as either a three port (Fig. 10) or six port (Fig. 11) nozzle is required. When these nozzles are air atomized, the... 

The parallel reactor for the screening of the titer-plates consists of several modules, each of them is responsible for just a single operation (Fig. 4.12). The gas flow for example is preheated and evenly distributed within the distribution module and delivered to the wells on the titer-plate. The latter is clamped between the distribution module and the insulation module and also treated as a separate reaction module. The insulation module separates the heated section of the parallel reactor from the unheated section and is further cooled by the heat exchanger module on top of it. The last module, just above the heat exchanger module, is a multi-port valve that delivers the product gas to the gas-chromatograph. 

Multi-port Valves, Injection Valves and Sensors... 

Multi-port valves belong to the key components in screening. Most equipment for analysis exists only in single-channel versions. Exceptions are, for example, radiation beam measurements of Atkins and Senkan [114] and tools for parallel analysis at Symyx. As long as equipment for parallel analysis does not exist for every type of desired measurement, multi-port valves will always be an essential part of every screening device. 

The optimum process for this binary separation would be to have fixed positions for the introduction of mobile phase and feed, and fixed collection points for the two components of the mixture whilst having the ability to move the stationary phase upwards. In practice it is impossible to engineer a system where the column bed moves, but it is possible to simulate the movement. Such a system is shown schematically in Figure 1.6 where four columns are set in sequence with four multi-port valves between the columns. 

Most computers built after 1997 have one or two flat ports in place of one DB-9 serial port. These ports are Universal Serial Bus (USB) ports and they are used for connecting multiple (up to 127) peripherals to one computer through a single port (and use of multi-port peripheral hubs ). USB supports data transfer rates as high as 1.5MBps. Additionally, USB cables can be a maximum length of 5 meters. 

For in situ reaction studies, an IR cell which approximates a continuously stirred tank reactor (volume = 1.5 cm ), equipped with 1/16" gas in- and outlet tubing and CaF2 windows, was used [12]. For the characterization of the surface species in the zeolite pores during the reaction, time resolved IR spectra of the catalyst were recorded as the activated zeolite was contacted with a He stream containing the reactants. Simultaneously, samples of the effluent gas stream were collected in sample loops of a multi port valve and subsequently analyzed by gas chromatography. This allowed to directly compare the type and concentration of the surface species with the rate of the catalyzed reaction. 

The multi-port selection valve of a sequential injection analyser can be regarded as an advanced commuting device, which selects one inlet port to be commuted to any one outlet port at a time. Also, the entire manifold can be accommodated in such a valve, leading to the lab-on-valve concept [84]. 

The basic components of the system are a liquid driver with only one carrier stream, a multi-port selection valve and a detector (Fig. 2.9). The valve is the heart of the sequential injection system and normally comprises 6—10 peripheral ports and a central port in a multi-position valve configuration. The central port is linked to a holding coil and the peripheral ports are connected to different solution aspiration tubes and transmission lines that are linked to different manifold components, e.g., detector and mixing chamber. Only one peripheral port is connected to the central port at any one time. Stream management inside the holding coil is accomplished by a bi-directional piston (or peristaltic) pump. The analyser is fully computer controlled and the injection volumes, residence times, delivery of solutions and analytical path lengths are selected based on a valve timing sequence and related flow rates. 

K. Yasuda, T. Kuroishi, Magic of multi-port valve for flow injection analysis, J. Flow Injection Anal 6 (1989) 5. 

Fig. 5.6 A schematic drawing of the VG ESCALAB 220i-XL photoelectron spectroscopy system. An analysis chamber, a multi-port carousel chamber, an evaporation chamber and a sample load-lock chamber are shown.

---