Hydraulics & Fluid Mechanics Trainers Lab Equipment Manufacturer, Supplier and Exporter in India

What this range covers

About fifty items, coded H-0001 onwards, and they are two things. The experiments: verification of Bernoulli theorem, metacentric height, forces of a jet, Reynolds apparatus, determination of critical velocity, losses in pipes and fittings, coefficients of discharge, velocity and contraction for orifices, discharge over notches, venturimeter, orifice meter and pitot tube. The instruments that make those experiments readable: piezometer tubes, differential manometers, a U-tube double column manometer, inclined tube manometers, a demonstration manometer, hook and pointer gauges, and a micrometer contraction gauge.

Two notes on our catalogue text. One record is listed as an office meter where an orifice meter is meant, which is a typo rather than an unusual product. And the Bernoulli apparatus has lost its apostrophe in our data, as several possessive names in this catalogue have. Several records also differ only slightly from each other - three hook gauge records, two venturimeter records, two differential manometer records and two inclined manometer records - so quote the code and the full product name together and ask for the specification of each record you are choosing between.

This is the third fluid mechanics range in this catalogue, and that is worth knowing

We would rather tell you than let you find out after ordering. The same subject appears in three places here, at different scales and in different styles of equipment, and the right answer depends on what kind of teaching you are doing.

Ask us to quote across all three against your experiment list rather than choosing from one page. For most teaching laboratories the sensible mixture is bench trainers for the routine experiments, one hydraulics bench for the modules that suit it, and one larger rig for project work.

The Fluid, the Datum, the Steady State

Three conditions decide whether any experiment in this listing produces a number a student can compare with theory. They are simple, they are rarely written down, and they account for most of the scatter in a fluid mechanics laboratory.

The fluid. A manometer measures a height difference; it reports a pressure only if the density of the liquid in it is known. So the manometer fluid is part of the instrument: water, a proprietary gauge oil of stated density, or - traditionally, for high ranges - mercury. Ask what fluid each manometer is supplied with and what its density is at the working temperature, because density changes with temperature and a reading taken on a hot afternoon is not the reading taken in the morning. And see the note on mercury below before ordering anything mercury-filled.

The datum. Hook gauges, pointer gauges and piezometer scales all measure a water level against a reference, and a level reading is meaningless until the datum is set and recorded. Worth teaching explicitly: a hook gauge is brought up to the surface from below and read when the hook just breaks the meniscus, a pointer gauge is brought down from above - and the two give slightly different readings on the same surface, which is why the method specifies one. Ask what resolution each gauge offers, how the datum is set and whether a vernier or micrometer movement is fitted.

The steady state. Every one of these experiments assumes steady flow. Readings taken while a valve is still settling, or while the supply tank level is falling, produce a smooth curve of the wrong thing. Ask whether the rig has a constant-head arrangement or an overflow weir, how flow is set and held, and how long it takes to settle. And bleed the manometer lines first: a single air bubble in a tapping line puts a fixed error into every reading taken afterwards and is invisible unless you look for it.

Before you order any mercury-filled instrument

Some differential manometers for high pressure ranges are traditionally filled with mercury. Mercury-added measuring devices are restricted under the international convention on mercury, with national rules that differ and that affect import, handling, storage, spill response and disposal - and the disposal obligation outlives the instrument. A mercury spill in a teaching laboratory is a serious and expensive event, and a dropped mercury manometer in a room with a carpet or a floor joint is a remediation job rather than a cleanup.

So ask us explicitly, for every manometer on the quotation: is it mercury-filled, and is an alternative fluid available for the range you need? For most teaching ranges a gauge oil or a water-over-oil arrangement will do the work, and where it will not, an electronic differential pressure transducer is now a realistic alternative with no restricted substance in it at all. We would rather answer that question at the enquiry stage than ship something you cannot lawfully keep.

The experiments, and what to ask of each

Bernoulli apparatus. The velocity head is calculated from the duct area, so the dimensions of the converging and diverging sections must be known accurately and stated in the manual. Ask whether the tappings are flush and burr-free, since a protruding or burred tapping reads a disturbed pressure, and ask how many tappings there are along the duct - more points make a better curve.

Reynolds apparatus. Needs a very steady, slow flow and settled water, a dye with a controllable fine filament, and patience. Ask whether a constant-head tank is included and allow the water to stand before the class. This experiment fails more often from a disturbed tank than from anything else.

Discharge coefficients - orifices and notches. These are the bread and butter of the subject, and the measurement that decides them is volume against time. Ask what collecting arrangement is supplied and whether it is gravimetric or volumetric; ask the notch shapes included, since rectangular and triangular notches give different exponents and a syllabus usually wants both; and for the orifice work, ask whether the contraction gauge for measuring the jet diameter is included, because the coefficient of contraction cannot be found without it.

Venturimeter, orifice meter and pitot tube. The comparison between these three on one flow is the most useful exercise in the listing for anyone heading into process or plant work: the same flow measured three ways, with three different permanent pressure losses. Ask whether they can be run on the same supply and compared, and whether the pressure tappings suit the manometers you are buying.

Metacentric height and forces of a jet are the two experiments students enjoy most. For the metacentric height apparatus ask the tank size, how the jockey weight is moved and read, and whether the pontoon can be loaded asymmetrically. For the jet apparatus ask which target plates are supplied - flat, hemispherical and conical give the classic comparison of momentum change - and how force is measured.

Services, room and what to ask for on the quotation

These benches need water and somewhere for it to go, a floor that tolerates being wet and sockets out of the splash zone with earth-leakage protection. Count the practical groups in one session and buy that many of the core experiments rather than one of everything - and remember that a rotation needs the experiments to take similar times, which is a question to ask us.

Ask for: the experiment and the quantities measured; duct and orifice dimensions stated in the manual; number and type of pressure tappings; the manometer supplied, its fluid, its density and its range, and whether it is mercury-filled; flow setting, constant-head arrangement and settling time; collecting tank and timing arrangement; gauge resolution and datum setting; bench or floor mounting, mass and footprint; water supply and drain requirement; nominal voltage, frequency and plug pattern where a pump is fitted; consumables and spares with prices - seals, tubing, manometer fluid, dye, gaskets; the worksheets supplied; and the warranty and local service position. For any certification stated here, contact us for the latest copies of the relevant certificates before you tender on it.

Related ranges: pump test sets and turbine test sets for turbomachinery, machines for thermodynamics and structures apparatus, process control and instrumentation for flow and level control, and chemical reaction engineering for unit operations. The full set is listed under engineering apparatus. For a quotation, send us your syllabus experiment list, the destination country, the class size in one session and the length of your practical slot.

Frequently asked questions

Are any of the manometers mercury-filled, and what are the alternatives?

Some differential manometers for high pressure ranges are traditionally filled with mercury, and this listing does not say which. Mercury-added instruments and elemental mercury are restricted under the Minamata Convention on Mercury in many markets, with national rules on import, handling, storage, spill response and disposal, so confirm the position with your own regulator before ordering. Then ask, for every manometer on the quotation, whether it is mercury-filled and whether a mercury-free alternative is available for your range. For most teaching ranges a gauge oil or water-over-oil arrangement works, and an electronic differential pressure transducer is another option.

Why don't our fluid mechanics results match theory?

Usually one of three conditions has slipped. The fluid: a manometer reports a pressure only if the density of its liquid is known, and density changes with temperature, so ask what fluid each manometer carries and its density at the working temperature. The datum: hook gauges, pointer gauges and piezometer scales are meaningless until the datum is set and recorded. The steady state: readings taken while a valve settles or a supply tank level falls produce a smooth curve of the wrong thing. And bleed the manometer lines first, because one air bubble in a tapping line puts a fixed, invisible error into every reading.

Should we use a hook gauge or a pointer gauge for water levels?

Either, but not interchangeably within one method. A hook gauge is brought up to the surface from below and read when the hook just breaks the meniscus; a pointer gauge is brought down from above. The two give slightly different readings on the same surface, which is why a method specifies one, and it is worth teaching explicitly. Ask what resolution each gauge offers, how the datum is set and whether a vernier or micrometer movement is fitted. There are three hook gauge records in this listing that differ only slightly, so quote the code and full name and ask for each specification.

What should we check on the Bernoulli and Reynolds apparatus?

For the Bernoulli apparatus, the velocity head is calculated from the duct area, so the dimensions of the converging and diverging sections must be stated accurately in the manual. Ask whether the tappings are flush and burr-free, since a burred tapping reads a disturbed pressure, and how many there are along the duct, because more points make a better curve. The Reynolds apparatus needs a very steady, slow flow, settled water and a dye giving a fine controllable filament. Ask whether a constant-head tank is included, and let the water stand before the class: a disturbed tank is the usual cause of failure.

What is needed for the orifice and notch discharge experiments?

These experiments are decided by volume against time, so ask what collecting arrangement is supplied and whether it is gravimetric or volumetric. Ask which notch shapes are included, since rectangular and triangular notches give different exponents and a syllabus usually wants both. For the orifice work, ask whether the micrometer contraction gauge for measuring the jet diameter is included, because the coefficient of contraction cannot be found without it. And ask whether the rig has a constant-head arrangement or overflow weir, how flow is set and held, and how long it takes to settle before readings start.

How many trainers do we need, and what services does the room need?

Count the practical groups in one session and buy that many of the core experiments rather than one of everything. A rotation also needs the experiments to take similar times, so ask us how long each takes. The room matters as much: these benches need a water supply and somewhere for the water to go, a floor that tolerates being wet, and sockets out of the splash zone with earth-leakage protection. Ask for bench or floor mounting, mass and footprint, water supply and drain requirements, and the nominal voltage, frequency and plug pattern wherever a pump is fitted.

Key takeaways

• Choose across three ranges: bench trainers here, a hydraulics bench with modules, and larger rigs for project and open channel work.
• The manometer fluid is part of the instrument: know its density at the working temperature or the pressure reading is guesswork.
• Ask about mercury on every manometer: confirm the Minamata Convention position with your regulator, and ask about a mercury-free option if one is required.
• Set and record the datum: a hook gauge reads from below, a pointer gauge from above, and the method specifies which.
• Steady flow and bled lines: unsettled flow and a trapped air bubble cause most of the scatter in a fluid mechanics lab.
• Compare three flowmeters on one flow: the venturimeter, orifice meter and pitot tube together show three different permanent pressure losses.

About this page

Ray Export is a manufacturer and exporter of laboratory, scientific and educational equipment based at Plot No. 449, HSIIDC Industrial Area, Saha, Ambala, Haryana 133104, India. Enquiries: [email protected], +91-9817319615.

Written by Palak Mall, Senior Content Writer. Technically reviewed by Arvind Kumar, Lab Equipment Specialist, 12+ years in laboratory and testing instrumentation. Last updated: 17 October 2026.

Specifications for each trainer - duct and orifice dimensions, number of tappings, manometer fluid, density and range, gauge resolution, flow setting and settling time, mass, footprint and services - are confirmed in writing on the quotation. For certificates, standards or approvals, contact us for the latest copies of the relevant certificates. No price is quoted on this page. Mercury: the listing does not state which manometers are mercury-filled; mercury-added instruments and elemental mercury are restricted under the Minamata Convention on Mercury in many markets, so confirm with your own regulator and ask us for a mercury-free alternative. Listing note: the range is given only as about fifty items from H-0001 onwards; one record reads office meter where orifice meter is meant; the Bernoulli apparatus has lost its apostrophe; and three hook gauge, two venturimeter, two differential manometer and two inclined manometer records differ only slightly.