HP-IB

Built-in HP-IB and RS-232 communication ports provide easy system interconnection and allow the GC to operate in diverse laboratory environments. 

Although in principle it is possible to simply use several GC instruments each equipped with a sample manager and a separate PC, this is really not efficient because it is expensive, and at the same time data handling becomes tedious. The first successful construction consisted of two GC instruments (e.g., GC instruments and data bus HP-IB) are commercially available from the firm Hewlett-Packard, Waldbronn, Germany), one prep-and-load sample manager PAL) (commercially available from CTC, Schlieren, Switzerland) and one PC 102). 

Parallel IEEE488 interface is a universal standard developed in closed cooperation with Hewlett-Packard, hence its designation HP-IB (Hewlett Packard Interface Bus). Other manufacturers call it GP-IB (General Purpose Interface Bus). This type of interface is very common in physical and electronic instruments, and also in HP instruments for chemical measurements. 

All of the mechanisms which have been detailed operate with electric impulses. The communication between signal transmitters and receivers must often allow language modifications to obtain compatibility (24). Electronic cards allow such changes they are serials-port type RS 232, HP-IB, IEEE, — These cards are placed in the complete management unit, i.e., the computer. The access to data and results is allowed by the computer software, which must remain as user friendly as possible. Programs are used as means of dialogue with the system and for calculation. 

Heavy-duty (material 100 Ib/fF). For extremely heavy duty (150-200-Ib/ft material), the maximum working capacity with 20-hp motor is 35 fF. 

In this continuous unit the output can range from 200-500 Ib/min with hp from 5 to 40 and r/min from 200 to. 300, depending on the materials mixed. 

The method used for grinding pressed cakes depends upon the nature of the cake, its purity, residual oil, and moisture content. If the whole cake is to be pulverized without removal of fibrous particles, it may be ground in a hammer mill with or without air classification. A 15-kW (20-hp) hammer mill with an air classifier, grinding pressed cake, had a capacity of 136 kg/h (300 Ib/h), 90 percent through No. 200 sieve a 15-kW (20-lm) screen-hammer mill grinding to 0.16-cm (Vi6-in) screen producea 453 kg/h (1000 Ib/h). In many cases the hammer mill is used merely as a preliminaiy disintegrator, followed by an attrition mill. Typical performance of the attrition mill is given in Table 20-25. A finer product may be obtained in a hammer mill in closed circuit with an external screen or classifier. 

Lead Oxides Leady litharge containing 25 to 30 percent free lead is required for storage-batteiy plates. It is processed on Raymond Imp mills. They have the ability to produce litharge that has a desired low density of 1.1 to 1.3 ff/cm (18 to 22 g/iu ). A 56-kW (75-hp) unit produces 860 kg/h (1900 Ib/h) of materialhaving this density. 

The Raymond ring-roll mill with its internal air separation is widely used to pulverize phenolformaldehyde resins. The usual fineness of grind is finer than 99 percent minus 200 mesh. Air at 4°C (40°F) is usually introduced into the mill to limit temperature rise. A typical 3036 Raymond mill using 34 kW (45 hp) will produce better than 900 kg/h (2000 Ib/h) at 99 percent minus 200 mesh. 

Flow rate, Ib/h (kg/h) Conveyor pipe, inside diameter, in (mm) Power required, hp Range of investment, f ... 

Wheel diameter, in Base steam rate, Ib/hp-hr Power loss, hp Total power, hp Steam required, Ib/hr Steam rate, Ib/hp-hr... 

The required suction pressure to the expander is not available until the oxidizer tower reaches design pressure. With two compressors in operation this takes approximately 15 min. Since the expander wheel is mounted on the compressor pinion, enough flow must be available at startup to prevent overheating. The calculated windage loss of the expander wheel (40 hp) requires about 16,000 Ib/lir of flow to prevent overheating. 

The theoretical steam rate (sometimes referred to as the water rate) for stream turbines can be determined from Keenan and Keyes or Mollier charts following a constant entropy path. The theoretical steam rate is given as Ib/hr/kw which is easily converted to Ib/hr/hp. One word of caution—in using Keenan and Keyes, steam pressures are given in PSIG. Sea level is the basis. For low steam pressures at high altitudes appropriate coirections must be made. See the section on Pressure Drop Air-Cooled Air Side Heat Exchangers, in this handbook, for the equation to correct atmospheric pressure for altitude. 

HP = Gas horsepower W = Flow, Ib/min Hpoiy = Polytropic head Had = Adiabatic head Ep = Polytropic efficiency Ea = Adiabatic efficiency... 

CORR. ALLOW.. HEADER A PARTmONS WatM Rnla ib/hp-hT. 

Because manufecturers tables are based on standard 0.075 Ib/fd air, this density difference must be recognized. According to Fan Law No. 6, if the rpm (speed) and cfm (capacity) are constant, the pressure and hp vary direcdy as the reladve density. 

First, for Figure 14-22, enter at the top at rpm and move to the first estimating turbine wheel diameter then read down to the TSR (calculated or from tables) at Ib/kw-hr read across to base steam rate in Ib/hp-hr. Note that the base steam rate is per hp-hr, and the TSR is per kwh (or kw-hr). Now correct the base steam rate for the horsepower loss (i.e., the portion of blades of turbine spinning outside the nozzle arc, creating friction and windage). From Figure 14-23, at the top read rpm at the exhaust pressure on curved lines noted cond, read down to the estimated wheel diameter, and read the horsepower loss on the left vertical axis. 

Willans line plot Figure 14-31 at partial load of 900 hp, the steam flow should be 27,000 Ib/hr. 

From the above it can be seen that 10 sqft of boiler heating surface was commonly considered to provide 34.5 lb of saturated steam, from and at 212 °F. Whereas, because of the much higher heat transfer rates today, modem boilers often generate anywhere from 100 to 500 Ib/hr of steam from the same heated surface area (3.5-0.7 sqft per boiler hp). 

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