Operating Labor

Virtuady ad new pdot plants wid be computer controded and heavdy automated due to the high cost of operating labor, need for high accuracy and repeatabdity, and ease of data gathering and work-up. Stand-alone computer and programmable logic controder systems wid continue to dominate the market because of their low cost and ease of use. 

Many improvements have been made to streamline performance and to reduce machine operation labor. Some of these are tensionless jigs using variable speed electric motors with built-in drag for brakes, automatic reversing equipment, and automatic temperature and level controls. These machines are widely used for goods that are easily creased, such as fabrics consisting of filament acetate, heavy filament nylon, or cotton duck. They are also convenient for small dye lots and for sampling purposes. 

The manufacturing cost consists of direct, indirect, distribution, and fixed costs. Direct costs are raw materials, operating labor, production supervision, utihties, suppHes, repair, and maintenance. Typical indirect costs include payroll overhead, quaHty control, storage, royalties, and plant overhead, eg, safety, protection, personnel, services, yard, waste, environmental control, and other plant categories. However, environmental control costs are frequendy set up as a separate account and calculated direcdy. The principal distribution costs are packaging and shipping. Fixed costs, which are insensitive to production level, include depreciation, property taxes, rents, insurance, and, in some cases, interest expense. 

Unit cost data should be carefully assessed to ensure that process type, size, and raw materials are similar to the proposed venture. Operating cost data sometimes are reported for separate categories such as operating labor, maintenance labor, supervision, and utiHties (9). 

Direct Manufacturing Costs Direct manufacturing costs include raw materials, operating labor, utihties, and some miscellaneous items. A summary of the characteristics of each follows. 

Operating Labor The cost of operating labor is the second largest item of expense in the manufac turing cost. Labor requirements for a process can be estimated from an intelhgent study of the equipment flow sheet, paying careful attention to the various primaiy process steps such as frac tionation, filtration, etc. The hourly wage rate should be that currently paid in the company. Once the number of persons reqiiired per shift has been estimated for a particular production rate, the annual labor cost and the labor cost per unit of production can be estimated. 

H. E. Wessel [Chem. Eng., 59, 209-210 (July 1952)] made a study of the operating-labor requirements in the United States chemical... 

The approximate cost of supervision for operating labor is equivalent to 10 percent of the labor cost for simple operations and 25 percent for complex operations. 

Payroh overhead includes the cost of pensions, holidays, sick pay, etc., and is normally between 15 and 20 percent of the operating-l or cost. Laboratoiy work is required for product quality control, and its cost is approximately 10 to 20 percent of the operating-labor cost. 

Table Type This is a simple flat metal sheet with slightly upturned edges and jacketed on the underside for coolant flow. For many years this was the mainstay of food processors. Table types are still widely used when production is in small batches, when considerable batch-to-batch variation occurs, for pilot investigation, and when the cost of continuous devices is unjustifiable. Slab thicknesses are usually in the range of 13 to 25 mm (V2 to 1 in). These units are homemade, with no standards available. Initial cost is low, but operating labor is high.

Performance and Cost Data for Turbo-Tray Dryers Performance data for three apphcations of closed-circuit diying are included in Table 12-29. Operating, labor, and maintenance costs compare favorably with those of direct-heat rotating eqmpment. 

Operating Costs Power cost for a continuous thickener is an almost insignificant item. For example, a unit thickener 60 m (200 ft) in diameter with a torque rating of 1.0 MN-m (8.8 Mlbf in) will normally require 12 kW (16 hp). The low power consumption is due to the very slow rotative speeds. Normally, a mechanism vi l be designed for a peripheral speed of about 9 m/min (0.5 ft/s), which corresponds to only 3 r/h for a 60-m (200-ft) unit. This low speed also means veiy low maintenance costs. Operating labor is low because little attention is normally required after initial operation has balanced the feed and underflow. If chemicals are required for flocculation, the chemical cost frequently dwarfs all other operating costs. 

Operating Labor Centrifuges run the gamut from completely manual control to fully automated operation. For the former, one operator can run sever centrifuges, depending on their type and the apphcation. Fully automatic centrifuges usually require little dirert operation attention. 

The engineer estimating the operating labor must visualize the plant operation, degree of automation, and the labor climate for the project being estimated. For most hydrocarbon processing plants, each control room should have at least one operator with no outside duties. For very large control rooms, more than one such operator may be needed. 

Every location has advantages and disadvantages that impact on the operating costs. Data must be collected for the proposed site and used to adjust historical data to get a proper estimate. Such costs as transportation, labor, and purchased utilities can be determined. However, such items as operating labor productivity, local customs, weather, and local management attitudes can only be estimated. 

Wessel, H. E. (1952) Chem. Eng., NY 59 (July) 209. New graph correlates operating labor data for chemical... 

Operating costs include the costs of raw materials, direct operating labor, labor supervision, maintenance, plant supplies, utilities (steam, gas, electricity, fuel), property taxes, and insurance. Sometimes certain operating cost components are directly expressed as a fraction of the capital investment cost. Table B.3 is a brief checklist... 

Operating supplies 0.5-1.0% of investment per year, or 6-10% of operating labor... 

Nelson-Farrar index of operating labor cost (wages plus benefits) 1955- 1999 (1956 = 100). 

Treatment systems should be demonstrated to be effective, and expandable (or reducible), in a stepwise modular fashion to ensure efficient design and operation. At many sites, it is cost-effective to install several temporary treatment systems in parallel configuration, and remove them as the need is diminished until the stable rate is achieved where a single unit can handle the load. After careful analysis, it may be determined that the best procedure is to install and operate the system at the projected long-term rate from the onset. Although this plan may extend the longterm remediation time, cost savings on equipment purchase (or lease) or initial operation labor may be justified. 

IRS Internal Revenue Service Y Operating labor operator-hour/ton... 

Operating Labor The most reliable method for estimating labor requirements is to prepare a table of shift, weekend, and vacation coverage. For round-the-clock operation of a continuous process, one operator per shift requires 4.2 operators, if it is assumed that 21 shifts cover the operation and each operator works five, 8-h shifts per week. For batch or semicontinuous operation, it is advisable to prepare a labor table, listing the number of tasks and the number of operators required per task, paying particular attention to primary processing steps such as filtration and distillation that may have several items of equipment per step. 

Supervision The approximate expense for supervision of operations depends on process complexity, but 15 to 30 percent of the operating labor expense is reasonable. 

Payroll Charges This item includes workers compensation, social security premiums, unemployment taxes, paid vacations, holidays, and some part of health and dental insurance premiums. The figure has steadily declined from 1980 and now is 30 to 40 percent of operating labor plus supervision expenses. 

---