Ultrasonic flow meters mainly include transit-time ultrasonic flow meter and doppler ultrasonic flow meter,transit-time flow meter is mainly for average fluid and doppler flow meter is for dirty fluid. Ultrasonic flow meter is famous for its clamp-on installing way.Clamp-on installing way can ensure many good features: no pipe cutting, no risk of leakage,no pressure loss,no flow stop,etc.

In order to meet versatile, ultrasonic flow meters have developed insertion sensor and inline type sensor.

As different standard,ultrasonic flow meters can be divided into the following:

1)Fixed installing and portable type

2)Transit-time and doppler

3)Gas flow meter and liquid flow meter

4)Battery powered and main powered

Some useful link about ultrasonic flow meter  and its manufacturers

1. Wikipedia About Ultrasonic Flow Meter

http://en.wikipedia.org/wiki/Ultrasonic_flow_meter

2.GE Ultrasonic Flow Meter

http://www.ge-mcs.com/en/flow.html

GE ultrasonic flow meters were gained by purchasing the company of Panametrics,and have ultrasonic flow meters for liquid and gas.

3. Siemens Ultrasonic Flow Meter

http://www.automation.siemens.com/w1/automation-technology-flow-measurement-18626.htm

Siemens clamp-on ultrasonic flow meters are gained by purchasing the company of Controlotron,based in U.S.A , and have clamp-on and inline ultrasonic flow meters.

4.Ultrasonic Flow Meters Basics

http://www.ultrasonic-flow.com/content/8-tech-info

Introduce some basic information about ultrasonic flow meters.

5.Ultrasonic Flow Meters with Low Cost and Good Performance.

http://www.ultrasonic-flow.com/

Supply low cost ultrasonic flow meter,portable flow meter,clamp-on flow meter,ultrasonic water meter,ultrasonic heat meter,ultrasonic thickness gauge.

6.Ultrasonic flow meter-portable ultrasonic clamp on flow meters

http://www.heremeter.com

Manufacture ultrasonic flow meter, clamp-on flowmeter,portable flow meters,low cost flowmeter,ultrasonic thickness gauge,BTU ultrasonic heat mete

7.Ultrasonic Doppler and Time of Flight Flow Meters

http://www.engineeringtoolbox.com/ultrasonic-doppler-flow-meter-d_495.html

An basic introduction to the ultrasonic Doppler and Time of Flight Flow Meters.

8.Ultrasonic flow meter transducer sing-around transit-time

http://www.d-flow.com/

Develop, manufacture and market your own ultrasonic flow meter for liquids and gases – for sale to end-users or integration in your own product!

9.Publication: Using Ultrasonic Flow Meters in Irrigation Applications

http://www.ianrpubs.unl.edu/pages/publicationD.jsp?publicationId=197

Several devices exist to measure water flow in pipelines. A relatively new alternative is the ultrasonic flowmeter.

10.Theory of Operation for Transit-Time Ultrasonic Flow Meters

www.ndd.ch/UserData/Download_00210_00.pdf

ultrasonic flow meters based on the principle of transit-time measurement. All ultrasonic flow meters of ndd Medical Technologies use this measurement

11.Piezoceramics in ultrasonic flow meters

www.noliac.com/Piezoceramics_in_ultrasonic_flow_meters-7913.aspx

Suppply piezoceramics which are used for sensors or transducers of ultrasonic flow meters.

Thermal mass flow meters belongs to mass flow meters which mainly have two kinds of flow meters, one is thermal mass flow meters,and the other is Coriolos mass flowmeter for fluid.Thermal mass flow meters is initially designed for gas,but now fluid thermal mass flow meters are also available.

Some useful links

1.Patent about ABB thermal mass flow meters

http://www.freepatentsonline.com/7650783.html

From the links, it can know the information about ABB thermal mass flow meters.A thermal mass flow meter is disclosed with at least one heating element which is mounted on a holder and immersed into a vessel with a flowing medium, wherein the holder is subdivided into two zones of differing thermal conductivity, the holder substantially having a high thermal conductivity adjoined by a short zone of low thermal conductivity in which the heating element is arranged.

2.Fluid thermal mass flow sensor – Patent # 5792952 – PatentGenius

http://www.patentgenius.com/patent/5792952.html

A fluid thermal mass flow meter including a composite flow tube having four tubular segments of high thermal conductivity formed in a length of tube made of a material having a relatively low thermal conductivity, a thin film element formed on the surface of and extending around each of the four tubular segments, circuitry for incorporating the elements into a bridge circuit, and a housing for containing the flow tube, elements, and circuitry.

3.Battery powered thermal mass flow meter for gas

http://www-static.shell.com/static/ecomarathon/downloads/2011/americas/redycompact_hydrogen_flow_meters.pdf

Thermal mass flow meters with battery power or external supply. Alongside numerous other possible uses, the red-y compact becomes an affordable alternative …

4.The Usage Of A Thermal Mass Flow Meter

http://www.flowmeterbasics.com/thermal_mass_flow_meter.html

Using something as complex as a thermal mass flow meter may be enough to scare

5.Discuss thermal mass flow meters

Http://wiki.answers.com/Q/how_thermal_mass_flow_meter_calibrated

A site can ask the question of thermal mass flow meters and waiting for others’ help and replies

6.General information about thermal mass flow meters

en.wikipedia.org/wiki/thermal_mass_flow_meter

Can find some basic information about thermass flow meters,may be not professional,but you may learn it simply.