Objective of laundry

Linen are destroyed mostly in the laundry, and less in usage.  Modern industrial laundry processes subject the linen to extreme physical and chemical conditions, reducing the life span of the linen.

During washing linen is exposed to high temperature, high chemical concentration, and subjected to the mechanical action of the large wash wheel.

During flatwork ironing they are subjected to stretching and pulling under high temperature.

The wear and tear caused by these processes are much higher than that cause by usage.

It is easy to wash the linen clean, by subjecting it to heavy soil washing disregard to the soil condition.  The cost of laundry increases, and the life of the linen reduces.

Therefore, the objective of a laundry is to process the linen to achieve desired hygiene and aesthetic standards, with minimum damage to the linen, ie to preserve linen’s life expectancy.

Life expectancy of linen

The life expectancy is the number of wash it lasts before it is condemned.

The composition of the linen affect the life expectancy.

Type of linen

Life expectancy

100% cotton:

200 wash

50/50 polyester cotton:

250 wash

Linen cost per unit CPU

The cost of the linen divided into the number of washes is the loss in value of the linen per wash.  Add to it the cost of laundrying is the cost per unit.


=   Weight of the item


=   Laundry cost per lb


=   Life Expectancy in number of launderings


=   Purchase price of the item

e.g.  A bedsheet cost $7.00, lasting 250 cycles of washing


=  1.5 lb


= $0.33


=  250


= $7.00

Notice that it cost $123.75 in laundering the bedsheet 250 times, which is 18 times the cost of the bedsheet at $7.00.  Therefore it is the number of laundering cycles that this item can withstand which is critical to the purchase decision of the bedsheet and not the initial cost.

The wise linen manager seeks optimal durability to wear and refurbishment, minimum weight, and minimising laundry cost per pound.

LC/# =  Total cost/total laundry processed

Total cost = wages + chemicals + water + electricity + steam + sewage charge



Utilities = Water + Electricity + Sewage + Fuel

Others: Packing


Several factors made body soap unsuitable for laundry use:

  1. Soap is made from natural oils such as animal fats or vegetable oils. Soap will react with all the hardness in the water first before it can react with soil in the linen.  Therefore, it is effective only for use with soft water i.e. hardness below 50ppm.  If water hardness is above 50ppm then detergent is more suitable.  Detergent is made from chemicals.
  2. Body soap is usually neutral; laundry soap works better with alkali builder.
  3. Body soap does not dissolve too readily in water, so that it lasts longer.  Laundry soap must dissolve as quickly as possible.  If there are soap specks which have not dissolved completely during the main wash, they will cause havoc in the washing and finishing processes.

Regulation requires steam boiler to be operated by certified boilerman.  However,  boilerman’s duties may not be properly understood.

A boilerman certificate is much like a driving license.  A driver is not a qualified motor mechanic who can repair a vehicle.  Similarly, a boilerman operates a boiler.  He is not a repair or service technician for the boiler.

Water level

Over eighty percent of all boiler accidents are related to low boiler water.  Therefore, taking good care of the boiler water will eliminate eighty percent of boiler problems.

A boilerman’s first task on entering a boiler room is to inspect the level gauge of the boiler and feedwater tank.  A common practice is to size the feedwater tank to cater for ten minutes of boiler firing at maximum continuous rating (MCR).  Ten minutes is the time a boilerman may leave the boiler room.


 The primary purpose of blowdown is removal of dirt, sediment and scale.  It is an essential part of every boilerman’s duty.  ASME has recommended blowdown procedure.  It differentiates operation of quick- and slow-opening blowdown valve.  This procedure is not well known outside of US and seldom practiced.

Blowdown of water column

Every boilerman knows that boiler blowdown is essential, however, many do not carry out water column blowdown regularly.

Warm start-up vs cold start-up

Starting up a cold boiler needs more time in order to reduce thermal shock to the boiler.  The boiler must be fired at low fire until it reaches steaming temperature.  The air vent on the top of the boiler should be open during this time to release air  trapped in the boiler.  It should be closed when steam starts to appear. The whole process may take from thirty minute to one hour.  Many owners bark at boilerman working longer hour than the boiler without realizing the harm it may occur to the boiler started too fast.  There are factories that operate boilers round the clock throughout the year, stopping only once a year for annual overhaul.  They demand that the boiler be heated up slowly and put back into operation no sooner than twenty four hours.

Boiler should be controlled by the first valve mounted on the boiler

This is ASME’s requirement, yet most boilers are controlled by the valve on the steam header.  The boiler nozzle valve is never operated.  Yet the steam nozzle vale is serviced during annual overhaul and the header valve is not.

Regulation requires steam boiler to be overhauled once a year.  Many owners aim only to get pass the mandatory inspection with the minimum stoppage and at the lowest cost.  However, there are many benefits which may be overlooked on a rushed overhaul, and some pitfalls which may cause future harm.  This article examines what boiler overhaul is about and the importance of having a detailed and proper overhaul.

Boiler annual overhaul is an annual health check of the boiler.  It exposes the interior of the boiler for examination much like a surgery.  Certain sign of problems is visible only when open up and should be properly investigated.  discover what may be wrong in its operation and what action may be required to preserve and possibly improve its health.  These are not observed by the Inspector nor recorded in the certificate issued.

A boiler annual overhaul includes following work:

  • Cleaning of pressure vessel, the fireside and water side.
  • Cleaning and servicing of first valves and fitting mounted on the pressure vessel. These include the steam nozzle valve, safety valve, feedwater valve, blowdown valve, water level gauges.  To ensure that water column reflects accurately the level in the boiler, the crossed fitting must be cleared.  This is often missed out.
  • Two inspections conducted by the Inspector.
  • First a visual inspection of the pressure vessel and the fittings to ensure that there is not cracks, or deformation which may endanger the operation at the approved steam pressure. Any tell tale sign of problems may have been removed by the cleaning.
  • A final inspection when the boiler is fired up to check safety features including flame failure and low water cut off.

When a boiler is open up, it is important to examine the following:

  • On the fireside, the formation of soot, its location, amount and thickness, any unusual colours each tells a story.
  • Fleky ashes settled at base
  •   unusual formation of soot on third pass but no soot on second pass
  • Similarly, on the waterside, the deposit may be in the form of mud, or sandy, or in broken pieces. A study of the deposit reveals effectiveness of the water treatment and any necessary change or adjustment to be made.
  • unusual deposit on firetube
  • The condition of the furnace reveals the firing of the burner, eg uneven colour, carbon deposit.
  • The colour of the diffuser plate and any sign of carbon deposit
  • Meet the Inspector. Get a firsthand report of the boiler health from the inspector.  Normally early sign of problems are not reported in the certificate.

As can be seen from above, these evidence is lost once cleaned up without examination.  The problems are not reviewed and no corrective action can be taken.

Thorough cleaning takes time, normally a minimum of three days are required.  An overnight rush job skips over many services and does not realise the full benefits of an annual health check.  Some symptoms may need to be brought to the attention of specialists such as the water treatment specialist, and it takes time.

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