How to Interpret Oil Analysis Reports

The ability to interpret oil analysis results is crucial for guiding decisions about preventive maintenance activities.This article will address the fundamentals of oil analysis and how to interpret the resulting reports.

Interpreting Viscosity Results


Viscosity is the most common test run on lubricants because it is considered a lubricant’s most important property. This test measures a lubricant’s resistance to flow at a specific temperature. If a lubricant does not have the right viscosity, it cannot perform its functions properly. A lubricant with improper viscosity can lead to overheating, accelerated wear and ultimately the failure of the component.


Measuring Metals: 
Elemental Spectroscopy


Analyzing an oil analysis report involves understanding the concentration of expected and unexpected elements in your oil. Some contaminants are picked up as the oil circulates and splashes off different machine components and surfaces. Other contaminants can enter the machine during manufacturing or routine service, as well as through faulty seals, poor breathers or open hatches. No matter how the contaminants enter the oil, they can cause significant damage.


Understanding Wear Limits


When reviewing the wear levels in your test results, look at the trend history of each machine, not just the recommendations from the original equipment manufacturer (OEM). OEMs offer good benchmarks, but it is not wise to just follow their recommendations because most machines are used differently.


For example, two identical pieces of equipment may have vastly different elemental spectroscopy results due to variations in load, duty cycle and maintenance practices. Their results might even show a variety of particle count levels. Both machines could still be considered healthy based on the trending of the analysis. 


Quantifying the Amount of Water


When free water is present in oil, it poses a serious threat to the equipment. Water is a very poor lubricant and promotes rust and corrosion of metal surfaces. Dissolved water in oil produces oxidation and reduces the oil’s load-handling ability. Water contamination can also cause the oil’s additive package to precipitate. Water in any form results in accelerated wear, increased friction and high operating temperatures.

Determining Oil Condition: Acid Number


Acid number (AN) is an indicator of oil condition. It is useful in monitoring acid buildup. Oil oxidation causes acidic byproducts to form. High acid levels can indicate excessive oil oxidation or additive depletion and can lead to corrosion of internal components. 


Understand pump install in series and parallel

CENTRIFUGAL PUMPS IN SERIES - HIGH HEAD
Putting your centrifugal pumps in series, or connected along a single line, will let you add the head from each together and meet your high head, low flow system requirements. This is because the fluid pressure increases as the continuous flow passes through each pump, much like how a multi-stage pump works.

For two different pumps, the head will still be added together on the combined pump curve, but the curve will most likely have a piecewise discontinuity (meaning to curve with protusions as pictured in in the 2nd pump curve below).

PUMPS IN PARALLEL - LOW HEAD / HIGH FLOW
Putting your pumps in parallel, or connected to any number of line branches so that each handles a division of the flow, will help you reach a low head, high flow operating point that a single pump cannot supply.

Going back to our pump curves, the combined curve for parallel pumps is created from the addition of the flow capacities of each pump. Two of the same pumps will result in double the flow while two different pumps will result in the addition of the flows.

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Keep the bearing cools

If the bearings properly designed and selection, there is little or no need to be concerned about temperature rises on bearings, under “normal” operating conditions. But there are a host of different conditions that can raise the rolling elements’ temperature to the point where it becomes a problem.

Here’s take a look at one of the factors that engineers can adjust to keep bearings cools.

In systems using oil bath or splash lubrication, bearing temperatures are quite sensitive to the level of oil in the sump. The common practice of setting the nominal oil level at the center of the bottom ball bearing ( so  h/d = 0.5 where h is oil depth or height, h, and d is diameter of the ball bearing) will work in most instances.

However, at extremely high speeds, even this level may not be enough. And if h/d is less than 0.5, you run the risk that imperfect maintenance or abnormal operating conditions will result in oil starvation and catastrophic bearing failure. In such cases, an oil flinger should be recommended to use. It provides an oil mist without requiring precise control of oil level.

Excessive heat generation reduce mechanical seal life

Excessive heat generation between seal faces will drastically reduce seal life. It typically occurs when a pump is flooded and/or the seal chamber is incorrectly vented before pump start-up that lead to excessive heat generation and dry-running.

Shaft run-out and elevated vibration levels may also cause interruption to the lubrication film established between mechanical seal faces during successful operation.

A mechanical seal is often the first visible point of a failure, but the root cause of failure may be located in a different part of the system. Using the correct piping system, verifying sufficient net positive suction head available, carrying out proper pump preparation and ensuring that pump functions are within the original equipment manufacturer's parameters are all important for reliable seal performance.

Understand the viscosity of motor oil

Picking the appropriate oil for your car's engine is very important. Before that let’s us understand the motor oil specification.

Viscosity [a fluid's resistance to flow] is rated at 0° F (represented by the number preceding the "W" [for Winter]) and at 212° F [represented by the second number in the viscosity designation].

So 10W-30 oil has less viscosity when cold and hot than does 20W-50. Motor oil thins as it heats and thickens as it cools. The more resistant it is to thinning, the higher the second number (10W-40 versus 10W-30, for example.

At the low-temperature end, oil has to be resistant to thickening so that it flows more easily to all the moving parts in your engine. Also, if the oil is too thick the engine requires more energy to turn the crankshaft, which is partly submerged in a bath of oil. Excessive thickness can make it harder to start the engine, which reduces fuel economy. 

A 5W oil is typically what's recommended for winter use.

However, synthetic oils can be formulated to flow even more easily when cold, so they are able to pass tests that meet the 0W rating.

Once the engine is running, the oil heats up. The second number in the viscosity rating--the "40" in 10W-40, for example--tells you that the oil will stay thicker at high temperatures than one with a lower second number--the "30" in 10W-30, for example. 

Bearing Protector to solve bearing premature failure

Mechanical seal type centrifigul pump, oftenly encounter bearing premature failure due to lubricant oil contaminate with water, where this water come from steam quenching for mechanical seal,  where the steam condensate travel through pump shaft entering the oil seal of oil compartment.

To solve this issue, a bearing protector is recommended to install. 

Ideally dual face bearing protectors, offering double the protection of a conventional single seal face design.

Possible cause of steam trap failure (2)

Improper drainage

In the diagram, one can see if the condensate discharge too high, or the drip leg to narrow , it will cause condensate cannot enter to steam trap smoothly

Possible cause of steam trap failure (1)

The trap outlet piping is submerged, the inlet pressure drops and dirty water or foreign object get sucked into the trap causing failures.

Steam trap doesn't have the function of check valve.
Below diagram shown how to do the correction:

Potential cause of Mechanical Seal failure

As study shown, mechanical failures contribute 24% of all mechanical seal failures.

Here I listed that 4 area that you need to pay attention to.

1) Alignment of pump

Shaft misalignment, coupling imbalance, and impeller imbalance can all contribute to mechanical seal failures.

2) Piping strain the pump

In addition, after the pump is installed, if you have misaligned pipes bolted to it, you will impart a lot of strain on the pump.

3) Pump foundation

You also need to avoid a bad base: Is the base secure? Is it grouted properly? Do you have a soft foot? Is it bolted correctly?

4) The right bearings

And last, check the bearings. If the tolerance of the bearings wears thin, the shafts will move and cause vibrations in the pump.

The belt's science: Select Correctly Install Effectively Never Compromise Efficiency.

Effective, correct installation will ensure your belt drive lasts longer and works more efficiently throughout its service life.

One of the most common mistakes – made in 70% of installations – is to fit a new belt to a worn pulley.

 This wastes energy and not only compromises the efficiency but also the lifespan of the new belt.

In fact, the kind of lifespan you can expect from a new belt decreases drastically depending on the pulley it’s fitted to:

• New belt / new pulley – approx.. 25,000 hours’ life
• New belt / worn pulley – approx.. 12,000 hours’ life
• New belt / severely worn pulley – less than 1,000 hours’ life

Often, the pulley won’t be replaced because it’s considered too costly to do so. But if a pulley with worn grooves is replaced at the same time as the new belt is installed, it will quickly pay for itself by restoring optimum drive efficiency, by lengthening the life of the belt, by reducing maintenance requirements and by minimising downtime.

Useful tips for Maximising Bearing Service Life

Every bearing has a pre-calculated service life, however research has shown that two thirds fall short of their potential lifecycle.
Here i listed down 10 points plan to help you to get the most from their bearings.

1. Select the correct bearing

2. Fix and align

16%  of premature failures are as a result of incorrect fittings. Adhere to correct fitting practices and you can help to extend the bearing’s service life and reduce costs over time.

3. Correct sealing arrangement

4. Maintain lubrication

36 % of premature bearing failures occur as a result of incorrect specification and the inadequate application of lubricant. Getting the right lubricant, in the right quantity and at the correct interval levels is therefore essential. 

5.  Monitor bearing condition 

6. Plan for replacement 

No matter how much you care for your bearings, they will need to be replaced at some point or another and condition monitoring can help you to plan for that replacement.

Pump maintenance - check the shaft run-out

Shafts get bent. The spinning impeller has unequal loading on in causing the shaft to deflect away from the volute throat. Constant deflection causes weakness and can lead to a permanent offset of the shaft leading to shaft run out. 

Shaft run out is bad for seals. It causes them to flex twice on every revolution of the shaft. At high enough speeds this can cause a vibration in the seal which allows the seal faces to OPEN. BANG failed seal.

So, it is important to  check the shaft of your pump for any damaging shaft deflections by using the Dial Test Indicator (DTI).

Single stage pumps should be checked near the seal running position but multi stage pumps should be checked at suitable intervals along the shaft as well as at the seal running position.

The run out should not exceed 0.002 inches or 0.05 millimetres.

Quick way to determine pump Head and Capacity by increase impeller diameter

Here I would like to share with you all the quick way to determine pump Head and Capacity by increase impeller diameter.

Normally centrifugal pump will have 10~20 % allowance if the impeller size increase to max.

For example : original impeller diameter D1 = 301mm  D2 = 320mm and pump head  H1 = 33

The new pump head H2 will be (D2/D1)^2 * H1

and for the pump capacity, as well you can do calculate in this formulae

Quick way to determine Q2 will be (H2/H1)*Q1

Safety valve spring length

Why in B.S code stated that the length of the spring should be less than 4 X OD of the spring?

Answer: 
If the height of compression spring is more than 4 times the spring OD, the spring could buckle sideways and rub on the housing wall.

Conventional gland packing Vs. mechanical seals

Thinking of making the switch from conventional packing to mechanical seals?
Before we make the decision, let’s read on for a basic understanding of mechanical seals, and how they differ from packing.

WHY DO PUMPS NEED TO BE SEALED? 
Let's go back to some pumping basics and review how a centrifugal pump operates. Fluid enters a centrifugal pump through the suction nozzle at the center of a rotating impeller. As the impeller rotates, its vanes fill with fluid, then force it out to the pump casing where it exits the pump through the discharge nozzle.
Unfortunately, the discharge pressure will force fluid back behind the impeller, where it attempts to exit by way of the rotating drive shaft. Attempts have been made by pump manufacturers to minimize this leakage through design, but the leakage won't be stopped entirely.

Some form of sealing method must be put in place to minimize the leakage.

USING PACKING AS A SEAL Packing materials were originally the sealing method of choice, using soft, flexible materials. It's a very popular method of sealing pumps because of its low upfront cost, easy installation, and readily available materials.

USING MECHANICAL SEALS The biggest benefit of using mechanical seals is the drastic reduction in leakage. That reduction in leakage also has an effect on a number of other things as well. Things like a safer work environment without a wet floor, fewer bearing failures caused by leaking fluid, no excessive wear on the shaft sleeve damage from packing.
However, Mechanical seals are complicated pieces of equipment, with a wide variety of materials and configurations to choose from, be sure that what you invest in is exactly what you need for your application.

Thumb of rules: If the medium use is water, gland packing will be the choice because of it convenience, but when come to flammable or oil base medium the mechanical shall be the top selection.

How to ensure quality tightening of flange's bolt

1) Calculate the minimum required bolt loads (refer to ASME Sec. VIII)

2) Calculate the tightening torque

3) Ensure bolt length are 2~3 thread out of nut

4) Slightly hand tighten the flange and measure the gap (to ensure even gap and keep the reading ad initial before gasket compress)

5) Tighten the bolts with applied torque and diagonal pattern

Canned pump assembly tips

The picture shows some of the tips in canned pump assembly :

1) do not forget the lock washer
2) locknut' plate do not forget to bend to lock it
3)and lastly the nut on the front plate make sure sucure fasten

Canned pump carbon bearing setting

In replacing carbon bearing(B012),fix the  carbon bearing into bearing housing after putting the sheet(S26) into a cutout on the outer side of the carbon bearing.

 Tighten the setscrew(231) until it contacts the sheet. At this time, it is recommended that carbon bearings rotate to the right-hand and left-hand slightly.

 If the setscrew tightening too much that may cause carbon bearing crack & tightening too loose that may cause carbon bearing turning when star up.