SSi

Characteristics of modern, energy efficient hydraulic systems

• Small reservoir volume (relative to flow rate)

• Most fluid in the system is in constant recirculation

• Pump output changes to meet system demand

• Duty cycle includes random flow changes and long time periods between changes

SSi

Increase in contamination level in the fluid(slug of contaminant released into the circuit by the filter)

reaches all components in a relatively short time

Typical time for the fluid to complete a full circuit from pump outlet to the pump inlet is 6 to 15 seconds

SSi

What is DFE and why we use it

• Average contamination levels relate to wear rates and mechanical failures.

• Maximum contamination levels cause operational failure.

• Operational failure occur when contamination levels exceed specified maximum values

• Sensitive components are at risk even if the are exposed to sort periods of exposure to increased level of contamination

SSi

Sensitive components will fail when their contaminant tolerance level is exceeded regardless of the length of time they operate in a clean environment

SSi

•Filters need to be rated for their ability to control contamination levels and maintain it below the specified maximum, under all operating condition

•Current filter ratings, other than DFE, are useful for comparing filters, to establish relative ranking, and are not designed to predict contamination levels in actual service

SSi

•Filters capture some of the ingressed contaminants

•Filters do not retain all of the captured contaminants

SSi

Purpose of the DFE test

• The Dynamic Filter Efficiency (DFE) test has been developed to measure contamination released (downloading) by the filter when exposed to flow changes

SSi

What is DFE and why we use it

• Variations in contamination levels are present during the duty cycle.

• Variations can exceed safe levels during normal operations.

• DFE is the test used to determine the maximum and the average contamination level a filter can control, in an operating system

SSi

DFE Test

• Determines maximum contamination level in a system during the life of the filter under conditions simulating actual operations (Not an arbitrary laboratory test cycle)

• Provides accurate real time data of the contamination level in the fluid

• All test parameters are fully defined and under control throughout the test.

• Can be used for evaluating any size filter • Can be used to evaluate a filter having any particle retention

capability

0

10

20

30

40

50

60

70

80

90

100

00:01:3300:05:4800:10:0300:14:2100:18:3900:22:5500:27:1300:31:3100:35:4700:40:0300:44:2100:48:39

0

50

100

150

200

250

4µ5µ6µ10µ14µ20µ25µdPPoly. (4µ)Poly. (5µ)

SSi

Filter Performance Steady Flow

SSi

Filter Performance Changing Flow

SSi

Test System Control Panel

• Automatic - operation is not affected by operator techniques• Does not require experienced operators• Does not require supporting laboratory facilities

– Gravimetric procedure• Does not require additional test stands for testing filters

– Capacity– Clean Flow DP– Element collapse

• Fast, accurate, repeatable, economical– Average test costs are a fraction of the cost of an ISO 16889 test– Test report is printed at the conclusion of the test– A new test can be started immediately after the completion of the previous test

DFE Test System

• Closed loop• Recalculating (no bypass loop)• Full flow trough filter• Contaminant released is re circulated to the filter• Same fluid throughout test (fluid is not introduced or removed during the

test)• Constant injection (rate relative to test flow)• All the contaminant is either in the filter or suspended in the fluid• Real time particle counting• Dynamic APC flow control• Self sufficient does not require experienced operators or additional test

stands and laboratory facilities to complete a filter test

DFE Test System cont.

SSi

Mil F 8815 /7 -12 Element

SSi

MIL F 8815/3-12 Housing

SSi

SSi

Particle Counts 3 mic (c) - up and down stream of restriction at ~3 mg/liters

upstream presure: 110 to 450 psi, downstream pressure 84-180 psi

cyclic flow: 12 gpm to 8 gpm @ 3 min on and 3 min off

0

2000

4000

6000

8000

10000

12000

14000

0 5 10 15 20 25 30 35

test time - minutes

# of particles /ml upcount1dncount1ISO max limit 3 mg/lISO min limit 3 mg/l

Filter Rating: 12 mic.Steady Flow Tests

test # s/ particle mic sizes> 6 10 14 20ln030037 93.08 99.9 99.99 99.99ln030036 93.91 99.97 99.99 99.99ln030034 94.04 99.93 99.99 99.99average 93.67667 99.93333 99.99 99.99standard deviation 0.520801 0.035119 1.3487E-06 1.3487E-06coeff variation-% 0.6% 0.04% 0.00% 0.00%

Average Filtration Efficiency -NO flow changes -steady

Repeatability within the Test Lab on an identical Element(using the closed- loop Dynamic Filtration Efficiency Test Stand at SSI Labs)

Conclusion:The variation in efficiency from element to element is acceptable .The variation is comparable to round robin tests on elements tested with ISO 16889 -steady flow test procedure

Dynamic Flow Tests

test # s/ particle mic sizes> 6 10 14 20ln030029 84.93 93.2 99.9 99.9ln030028 92.2 99.93 99.99 99.99ln030030 92.15 99.89 99.99 99.99average 89.76 97.67333 99.96 99.96standard deviation 4.182977 3.874072 0.051961524 0.051961524coef variation-% 4.7% 4.0% 0.1% 0.1%

Lowest Filtration Efficiency after the flow change

Conclusion:The variation in efficiency from element to element is acceptable .The variation is comparable to round robin tests on elements tested with ISO 16889 -steady flow test procedure

Repeatability within the Test Lab on an identical Element(using the closed- loop Dynamic Filtration Efficiency Test Stand at SSI Labs)

SSi

Particle Size Vs. Efficiency-Average- Steady Flow Filter Effciency test on SSI's test stand

(similar to ISO 16889-except for closed loop recirculation-dirt injection)

020406080

100120

1 10 100

Particle Sizes- Microns

Efficiency -% time weighted avg.

ln030037ln030036ln030034

COV-% on micron size at 99.5% efficiency is << 5%

SSi

Efficiency variation from Element to Element using DFE Procedure-dynamic test (Cycling Flow) on SSI's Test Stand

0

20

40

60

80

100

120

1 10 100

Micron Sizes-microns

Efficiency -lowest- after the flow change from low

to high

LN030028LN030030LN030029

COV-% on micron size at 99.5% efficiency is << 5%-

`

SSi

Efficiency & Capacity Variations depending on the cycle frequency and the method used for testing

52

76 77

30

3.57 2.57 4.03 4.880

102030405060708090

0.1 Hz- DFE 0.1 Hz -ISO-Pall-unsynchronized Steady Flow Dynamic Filtration Efficiency (DFE) -3 min High Flow-3 min Low Flow

Minimum Efficiency -%(or) Capacity -gms

Min. Efficiency @ 5micronsCapacity -gms@ 90 psid

Tested Element- Typical Glass Media - conforming to (AN 6235-4-Pall 9020) size-Aftermarket 6 mic(c)

TEST #S: 020081/83/88/181;TEST DATE: May 2002