Purchasing special situations

When the required shaft horsepower for power input to an item of process equipment is less than 100 Hp, an electric motor is usually the selected drive. For higher horsepower input, consideration is given to combustion gas turbines, steam turbines, and internal combustion gas engines. However, except for remote, mobile, or special situations, steam turbines are the most common alternative to electric motors. Furthermore, steam turbines are considerably more efficient, 50-80%, than gas turbines or engines, which have efficiencies of only 30-40%. Equations for f.o.b. purchase costs of steam and gas turbine drives are included in Table 16.32 as a function of shaft horsepower. 

The degauss feature should not be used every day. Once a month is usually sufficient if you are having color or clarity problems that get worse with time. You would only have to degauss every day if you lived in a place where high magnetic fields are a problem. If that s the situation you find yourself in, you might need to purchase a special, heavily shielded monitor for those conditions. 

For either situation (i.e. of a special or common standard component) the purchaser must document the component specification. The specification must be approved and authorised by the relevant departments of the organisation and accepted by the supplier as the contract specification. 

To safeguard against such a situation arising, a first step can be taken after a grade of carbon has been tentatively selected for purchase. For this, a laboratory study is conducted in which the process liquor is treated with different batches of that grade of carbon this will disclose whether special quality controls are needed to ensure trouble-free shipments. 

A further complication when one makes comparisons is that in particular situations the prices charged may differ from the norm. It has already been noted that a company may charge different prices in the public and private sectors. In addition special discounts may be offered to bulk drug purchasers such as hospitals and retail pharmacy chains, and such discounts may or may not be passed on to the ultimate payer. Where these practices are widespread they can signihcantly affect the actual hgures, both as regards true margins and consumer prices. 

Figure 3 shows the high pressure network (70 bar and 16 bar) under operation and the location of a big underground storage of the aquifer type, which was exploited for seasonal equalisation of gas purchase. More details of high pressure transportation are given in /3/. Let us at first have a look on the present situation and special problems caused by different qualities. 

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