The Value Rating
The easiest way to select the best filters for your gas turbines
Selecting the right filters for your gas turbines is one of the most important decisions you can make for your facility. The right filters keep your gas turbines running at peak efficiency – eliminating fouling, reducing maintenance and boosting power output. The Value Rating was developed to help GT operators easily compare various filters and gain a quick understanding of the impact each filter will have on turbine performance.
The Value Rating - New Rating System is the Easiest Tool for Selecting Air Filters
The Value Rating Calculator
Get The Value Rating for your GT filters with this calculator. You can use filter data from most third-party test reports, but you’ll need to ensure that the test conforms to certain paramenters. Follow the simple instructions below to get started.
(click to expand)
Validate Test Conditions Before Starting
External 3rd party test should use standardized dust, but suppliers or customer can request specific test parameters. Please ensure that your test reports specify “ISO Fine” dust as performance can vary by a factor of 2x - 3x depending on the dust type.
The Value Rating uses test standard ISO 29461-1, as this report entails all necessary data to calculate The Value Rating of your filter. In case you do not have this report, you can use ISO 16890 for lower class filters and EN1822/ISO29463 reports for higher class, EPA-grade filters. Keep in mind that for higher class filters, EN1822/ISO 29463 does not contain dust holding capacity (see point 7). With the ISO 29461-1 standard you can use this test report for all filter classes from T1 – T13.
This field on the calculator is for your reference. Enter the name of the filter here. The information in this field will not affect the calculations or the results.
This field on the calculator is also included for your reference. Enter the airflow as tested. Filter performance and turbine impact varies greatly based on airflow, so test airflows should be exactly the same and relevant to your application and operation. Typical airflow for barrier filters would be 4250m3/hr or for conical-cylindrical set 2500m3/hr.
ISO ePM1 Minimum Efficiency Percentage
For this data it is important to refer to the data tables of results, and select the ePM1 minimum discharged efficiency not the average or reported, for comparable results. The ePM1 minimum efficiency is often reported as ePM1 min.
Efficiency Percentage at the Most Penetrating Particle Size
This is the efficiency at the most penetrating particle size, which is typically between 0.1 and 0.2um for EPA filters.
Initial Resistance (Pa)
This is the clean and new pressure drop of the filter at the rated airflow. It ensures that allcomparable filters are being evaluated with the same airflow.
Resistance After Loading 250g of ISO Fine
This information can be found in either the graphical representation of dust fed against resistance or pressure drop, or the data table associated with it. When the exact point is not available, the data may need to be interpolated.
The dust holding capacity is typically not performed as a standard for EPA filters tested according to EN1822 but can be requested from any 3rd party laboratory. It is important to compare this data point at the same airflow, using the same dust.
With the ISO 29461-1 dust holding capacity is tested for the full range of products T1 – T13. This value can be found in the report directly.
The Value Rating Explained
The information provided on the Value Rating Label helps you balance theeconomic impact of pressure drop and fouling caused by filters. The calculations combine information from the various filter test standards and gives weight to filtration efficiency, pressure drop and dust holding capacity.
The Output Rating is a projection of the average yearly power degradation you can expect from turbines due to fouling caused by particles getting past the filters. This value is based on the filter’s efficiency and the estimated impact of pressure drop on turbine output. We use a standardized scenario with an average PM2.5 ambient dust of 30ug/m3 and carefully selected and analyzed OEM published degradation levels by filter class to create an accurate projection.
The Fuel Penalty indicates how much more fuel you must use to compensate for degradation due to fouling and pressure drop. A perfect filter with 0 Pa pressure drop and 100% efficiency would get a +0% rating. A final filter with a +3% rating indicates the turbine will use 3% more fuel than if it was perfectly clean.
If you’re running at part load, you won’t see a direct impact of degradation on engine output, but you will see an impact on your fuel budget!
When you use better filters, you can minimize performance degradation and reduce emissions. The CO2 SAVINGS indice compares each filter to a T5 / ISO ePM10 60% filter – a basic, industry-standard entry-level final filter. Based on the Output Rating and Fuel Usage for the filter, the CO2 SAVINGS value estimates how many tonnes of CO2 you could save per year for a 125MW engine.
1The standardized environment assumes PM 2.5 value of 30ug/m3, 8 000h per year with a heat rate of 8 000kJ/kWh. In order to isolate the impact of the filters, the degradation number assumes the engine starts clean with no offline water washes performed during the year.