Dairy Plant Management and Pollution Control

Module 4. Working conditions

Lesson 8
SECURITY FOR PLANT AND MACHINERY AND THE EMPLOYEES

8.1 Introduction

Careful and proper operation of the plant will save it from damage and ensure trouble free operation. There are certain simple operational precautions which must be followed by the plant personnel. These in turn shall result in a sustained well being of the plant equipment, assisting in the maintenance of good hygiene and sanitation in the plant.

8.2 Safety Precautions During Cleaning Operation

8.2.1 Tanks and vats

• When cleaning large tanks or vats having agitator, the agitator switch should be locked and switched on before filling the product.

• While cleaning manually, a sturdy, four legged step ladder should be used to enter and to come out from the tank and clean the inner surface of the storage tank. Using can as a stool to enter or jumping out of a vat is dangerous.

• The ClP line should not be connected with the tank before the completion of manual cleaning. Also manhole of the tank should be kept open.

• Replacing of agitator gear box or motor should be done with utmost care.

• The light glass bulbs should be connected preferably with 24 V-DC power supply and proper earthing.

• For tightening the over head S.S pipe joints and fittings, the four legged step ladder or long hook spanner should be used.

• All the pipe lines should be clamped properly with supports.

• Pump parts, valves, sanitary fittings, etc., should be handled carefully during washing and sterilizing operations in order to protect the machined surfaces.

8.2.2 HTST pasteurizer

• Drain the brine solution, if used as cooling medium, from the pasteurizer. It may corrode the plates at high temperature.

• Disconnect separator and / or clarifier to prevent non- stainless steel parts in them from coming into contact with nitric acid.

• All other piping used during operation should be connected while cleaning.

• Filters if provided should be cleaned manually after dismantling.

• Strong solutions of the detergents should not be used.

• The cleaning temperature should not be exceeded with any detergent.

• Detergents should be taken gradually to avoid high local concentration. Solid detergents such as caustic soda and TSP should be dissolved in 2-3 liters of water before use.

• If air enters the plant, the plates may get a burnt - on coating which would reduce the heat transmission ability and increase the risk of corrosion. So, immediately after starting the plant, the air should be evacuated through vent cocks.

• Fine sand - like deposits may take place in the plate heat exchanger, possibly from the water supply, the detergents used, the raw milk etc., building up at the bottom of plate passes. Scraps of debris may be trapped at plate contact points. This also can lead to corrosion of the plate surfaces. Whenever water stains appear on the outer surfaces, a good quality metal polish should be rubbed vigorously following the grain of the finish. On any account abrasive, steel wool, or wire brush should not be used on stainless steel surfaces. The following care should be taken on the pasteurizer plates:

• Periodic inspection of individual plate surfaces is essential.

• While the plant is opened for manual cleaning, both the sides of the plates should be checked for scaling.

• The surface should be very clean to avoid corrosion of plates.

• Cleaning should be done with nylon, fiber brush or coir and washing soda only. Never use wire brush, otherwise scratches may damage the plate surfaces.

8.2.3 Homogenizer

While cleaning the parts, use brushes only. Do not use metal sponges around these parts as particles of metal can lodge in the cylinder and be pressed into valve seats, plungers, etc., when operation is started.

Be careful not to allow metal parts to strike each other or other metal objects.

Only 3-way valves to be provided at feeding in and out.

8.2.4 Milk condensing plant

• It is always best to change over from milk to wash water while evaporator is still running and at the same time, to reduce the steam pressure, so that, the tubes are flushed with a good flow of hot water. This should be continued until the tubes are clean.

• It is important to use soft water for washing since the use of hard water will cause scaling in due course of time.

• When the plant is dismantled for cleaning, the parts such as covers, manholes, distribution plates, etc., should be kept on rubber mat to avoid any damage.

• Check that the condensing system including pre heaters is well cleaned.

• Carry out physical inspection of calandria tubes using flash light by removing top and bottom covers.

• Use only soft metal brushes like brass, copper and nylon for cleaning the evaporator tubes. Never use steel wire brushes.

• After cleaning, proper care should be taken while assembling the parts.

8.2.5 Butter and ghee sections

• The floor should always be clean and dry.

• Whenever milk, cream, butter or ghee spills on the floor, the floor should be cleaned with teepol solution and hot water.

• Only trained operators should operate the butter churns and butter packing machines.

• After closing, the butter churn door should be locked properly.

• Floor near ghee boiler should not be slippery

8.3 Safety Precautions for Handling Hazardous Chemicals

• Instructions for handling hazardous chemicals should be prominently displayed.

• All containers should be clearly marked ‘ACID’ or ‘POISON’ as the case may be.

• While manual handling, barrels or drums full of caustic and other chemicals should be handled by at least two persons.

• A non-corrosive bottle carrier should be used while transporting acid bottles from storage to the plant.

• Employees opening containers and / or handling acids and poisonous chemicals should wear personal protective equipment such as rubber aprons, splash proof goggles and long sleeves over rubber gloves.

• While opening the chemical containers, the opener provided should be used and metal covers used after the drum has been opened.

• When removing acid from containers, tilting cradles or acid siphon and pumps should be used.

• After removing acid or caustic solution, the container should be closed properly and kept away from each other.

• Containers of caustic soda should be stored in a place away from work areas or passage ways.

• If caustic gets on the gloves or equipment it should be washed off immediately with sufficient quantity of clean water.

• Cleaning agents should not be mixed with hot water having a temperature of 450C under any circumstances.

• Usually, while feeding the washers and CIP tanks, chemical solutions should be made in a separate tank and, if possible, gravity flow should be used.

• While manual cleaning, the detergent solutions used may be neutral or slightly alkaline to avoid skin irritation.

8.4 Hygiene Precautions

• Clean protective clothing must be worn. 'NO SMOKING’ notices observed and all tools and equipment must be carried in closed tool boxes or bags.

• During maintenance operations, precautions must be concentrated on preventing the food product from being contaminated by extraneous material.

• It is therefore, essential that all fastening devices are secured firmly and that only fixing part such as washers or split pins used are non-corrosive when likely to be in direct contact with the product or passing above the product.

• Oil, grease, solvent and compounds used on food machinery must be those recommended for such use.

• Glass instruments such as thermometers must be properly encased, so that, they remain in position, even if broken.

• There must be no leakages on utility services, especially steam, refrigerants and cleaning solutions.

• Recycled water system must be frequently tested.

• Cleaning nozzles in washing devices must not be blocked or excessively worn-out.

• Storage area must be adequately ventilated.

• The balance tanks must be covered during the processing operations.

8.5 Plant House – Keeping

• Floor should be maintained clean, dry and non – slippery.

• Whenever milk spills on the floor during receiving and packaging operations the floor should be immediately hosed and cleaned.

• Rubbish and damaged tins and bottles should be kept in bins especially meant for them.

• Milk cans, butter-oil tins, powder bags / containers, cases, cartons and rubber mats for cleaning should be piled only in designated areas.

• Dark areas should be artificially lighted and floors and stairways kept free of accumulated rubbish, broken glass, S.S. pipe lines, fittings and gaskets.

• Once a maintenance task has been completed, all debris, tools and equipment must be removed and the plant left ready for cleaning and sterilizing operations.