FAQs | Frequently Asked Questions - Classic Filters

These Frequently Asked Questions (FAQs) are to provide a better understanding of terms and topics to do with gas and liquid filtration and to answer the questions we regularly receive.

Units of Measure

What does Nm3/hr mean?

Normal Meter Cubed per Hour. Unit used to measure gas flow rate. The ‘Normal’ refers to normal conditions of 0degC and 1 atm (standard atmosphere = 101.325 kPa) – for practicle purposes this is rounded to 1 bar.

What is scfm?

Standard cubic feet per minute. Another common unit to measure gas flow.

How big is 0.1 micron?

0.1µm is 0.0001mm. There are 25,400 microns in one inch

What does PPM mean?

Parts per million. 1 PPM = 0.0001%

How can I convert scfm to Nm3/hr?

1 scfm = 1.669 Nm3/hr

How can I convert from bar to psi?

1 bar = 14.5 psi

How can I convert from psi to bar?

1 psi = 0.069 bar

Filter Elements

What are borosilicate glass microfibers?

The microfibers are made from borosilicate glass. This is a type of glass produced from silica and boron oxide. Borosilicate glass has a very low coefficient of thermal expansion.

How big are the microfibers?

Depending on the grade of the filter element being produced the microfibres range in diameter from 0.25 to 5.0 micron.

What does “bonded” mean?

A bonded disposable filter element uses a binder to hold the mircofibres together give the filter media structure and strength. Typical binders and epoxy resign, PVDF (Kynar), silica and silicone.

Do disposable microfibre filter elements need seals?

No, because the bonded filter elements are self-sealing, by the use of axial compression, seals are not needed.

Do I need a support core for gas applications?

Usually support cores are only needed for disposable filter elements when used of liquid applications. Support cages can also be used on the outside of disposable coalescing filter elements.

Can you produce filter elements with custom dimensions?

We regularly supply special size filter elements with a range of diameters from 6mm up to 150mm and legths from 10mm up to 1000mm.

What is the correct flow direction for disposable filter elements?

Single layer particulate filter elements should flow outside to inside through the filter element.

Two layer coalescing filter elements should flow inside to outside through the filter element.

What is coalescing?

To coalesce is to combine elements together. Coalescing filters are designed to separate two phases – normally it would be to remove a liquid from a gas but they can also be used to separate two liquid phases liquid/liquid coalescing.

Why does a coalescing filter element flow inside to outside?

As the wet gas passes through the filter element aerosols and droplets are captured by the fibres and they then flow together and build to larger droplets. As the droplet breaks thought the outside surface it is kept there by surface tension until it becomes large enough to overcome gravity when it will run down the outside of the filter element and collect in the housing bowl.

I have a filter housing from a competitor. Can you supply replacement filter elements?

Our filter elements are based on industry standard dimensions and grades so we can offer complete interchangeably for competitor products. We will save you money too!

What is delta P?

Delta P, or differential pressure, is the measurement of pressure drop across the filter element. Typically our filter element flow rates are calculated using an initial dry pressure drop of 0.1 bar (1.5 psig).

Filter Housings

How many ports do I need?

Usually an end-of-line filter will have one port. An in-line particulate filter housing will have 2 ports and a coalescing filter housing will have tree ports – the third port in the bowl is to allow removal of the liquid. Sometimes the third port will have a manual or automatic drain.

What pressures can the filter housings be used for?

Housings can be used for negative and positive pressure applications giving a range from total vacuum to over 1300 bar.

Can you make me a special housing?

We can supply special housings from a single custom housing up to production runs of 1000’s.

Can you make filter housings in special materials?

Yes, we have experience of filter housings in a huge of materials. Click here for more information.

Can you supply housings coated for special applications?

We regularly supply housings with coatings like Sulfinert, or SilcoNert to use the new brand name, and we can do other coatings as well.

Can I have a filter housing with additional ports?

No problem. Let us know how many you need and where they should be positioned.

Do you charge to design a special housing?

All design work is free of charge.

Can you supply CAD drawings?

We can produce 3d and 2d drawings in several CAD file formats. Let us know what you need.

I have a filter element from a competitor. Can you make me a special housing for it?

No problem. Let us know what you need.

What is a CE mark?

A CE mark is making requirement of the Pressure Equipment Directive 2014/68/EU. For more information about CE marks click here.

What port threads can you produce?

Our standard port thread is NPT but we also supply filter housings with BSPT, BSPP (G threads), SAE threads, high pressure Autoclave and HiP threads.

Do you make housings with flanges?

Yes we have a special range of housings with flanged connections and have experience of these flange types –

• ASME/ANSI B16.5 – 1996 – Pipe Flanges and Flanged Fittings

• British Standard BS 4504 – Section 3.1:1989 – Circular Flanges for Pipes, Valves and Fittings

• SAE J 518 C – SAE Flanges Standard

Is 316L the only stainless steel you use?

For our standard, stocked filter housings we only use 316L stainless steel that has traceability back to the mill. Other grades of stainless steel can be supplied including 303, 304, Duplex and Super Duplex etc.

Can you supply material certificates to EN 10204-3.1

All our stainless steel housings have a serial number that gives complete traceability back to the mill. We can offer material certificates to EN 10204-3.1standard.

What other certificates can you offer?

Typical certificates include material certificates to EN 10204-3.1, Certificates of Conformity, Pressure Test certificates, Leak Test certificates and Certificates of Origin.

Other questions

Do you have ISO 9001?

Yes, we are operating a quality management system to ISO 9001. Our certificate can be found here.

Do you know someone who can manufacture a component for me which is not filter related?

As well as manufacturing bespoke filter housings we often help our customers by manufacturing parts they are having difficulty getting made no matter what they are. Send us a drawing and we’ll see if we can help .

Can you ship using my courier account number?

We can ship on our account or your account and can arrange shipping and collections from all the major courier companies.

If I have an urgent order can you ship directly to my customer?

Email through your order with your delivery paperwork and delivery details and we will send it as per your instructions.

Can you label your product boxes with my logo and label?

We supply this service to a number of our customers, please supply the artwork and product codes if required and we will do the rest.

Can we place a call-off order for regular shipments?

We can set-up regular shipments for your call-off orders, or have a more flexible system where the items are called-off when required.

Do you offer “bonded stock” solutions for items we use on a regular basis?

We are happy to discuss all options of “bonded stock” and work with OEM customers to ensure their requirements and fully met.

Have a question for us? Call us on +44 (0)1634 724224 or email us your requirements to [email protected]