Neometrix / Sampling & Analysis / Closed Sampling System / NMX-CSM-90

NMX-CSM-90 · ENGINEERED-TO-ORDER CLASS — SURVEY · TAP · LOOP · CLOSE · INTERLOCK · PROVE

Closed Sampling System. Nothing may change on the way.

Name: Closed Sampling System
Brand: Neometrix
SKU: NMX-CSM-90

A closed sampling system takes a sample of a process stream and brings it to a sample cylinder or to an analyser, without letting it out to the air and without changing it on the way. Neometrix engineers it as a system: the probe and the tap, a fast loop, a conditioning panel, a closed cylinder station, the purge and the return, and the interlock.

So the system has to take the sample from the live stream, bring it fast and unchanged, and give the rest back to the process, never to the room.

Discuss a closed sampling system Capability note (PDF)

A closed sampling station on a plain white studio background: an open rectangular brushed stainless frame with a flat stainless back panel and a shallow drip tray, an upright polished stainless sample cylinder held in two clamps with a valve block at each end, a vertical manifold of three-way ball valves with blue, red and yellow handles and two needle valves with black knobs, a small filter housing and a glass-tube flow meter joined by neat stainless tubes, and no people

Fig · 01 — A closed sampling station: a sample cylinder with a valve at each end, a manifold of three-way valves, a filter and a flow meter on one stainless frame — illustrative render.

The result

a sample that is trueof the stream, and not of the line

The speed

a fast loopso the sample is of the process now

The state

kept as it wasabove its drop-out temperature, at its own pressure

The closure

purged and returnednever vented to the room

Status

engineered to orderno delivered installation claimed

ISO 9001ISO 14001ASTM D3700 reference practice

Overview

Why a sample is easy to take, and hard to take true.

Because a sample can be wrong in three ways: it can be old, it can be changed, and it can be spilt.

A gas sample conditioning panel on a plain white studio background: a pale grey back plate on a slim stainless stand carrying a pressure regulator with a black knob, a filter with a clear bowl, a glass-tube flow meter, three needle valves and a pressure gauge turned away from the camera, joined by bright stainless tubes, with a plain pale grey analyser enclosure beside it connected by two narrow tubes, and no people

Fig · 02 — A conditioning panel: a regulator, a filter, a flow meter and needle valves joined by short stainless tubes, with the analyser beside it — illustrative render.

Nothing may change on the way.

What the system is for

It takes a sample of a liquid or a gas from a process line, for the laboratory or for an online analyser. It takes it safely, and it takes it in the state the stream was in.

Why the sample comes from the live stream

A sample from a dead leg or a drain is a sample of what has been standing there. So the probe reaches into the stream, and the tap is put where the flow is, so that the sample is of the process as it is now.

Why a fast loop

A long line makes a sample old before it arrives. A fast loop keeps the stream moving past the sampling point and returns the unused part to the process, so what is sampled is what the process is doing now. The return point is at a lower pressure than the tap, so that the loop flows.

Why the pressure is let down at the tap

In a gas line a lower pressure gives a shorter delay, and a smaller volume to hold. A filter or a pot holds old sample and mixes it with new, which adds delay. So the pressure is let down early, and every extra volume in the line has to earn its place.

Why the sample must not change

A cool line can drop a vapour out as a liquid. A pressure drop can flash a liquid into vapour. A long wall can hold a sticky component back. So the line is short and small, heated where it must stay above the temperature at which a vapour drops out, and held at the pressure that keeps the sample as it was.

Why closed, and why purged

Venting a sample to the air exposes whoever is standing there, and releases what the process was holding. So the cylinder is purged with the stream and filled through closed lines, and what is flushed out goes back to the process, to a return line or to a flare, and never to the room.

Why the valves are interlocked

A cylinder that is filled before it is purged holds air and the last sample. A line that is switched in the wrong order is spilt or dead-headed. So the three-way valves have interlocked handles, and the steps can only be taken in order.

Why the proof is a test and a comparison

A sampling line is proved by a leak test, by a measurement of its lag, and by a comparison with a sample of known composition. A line that looks right can still give a wrong answer.

The method

Survey, tap, loop, close, interlock and prove.

Six steps in a fixed order. The survey and the proof are the two that a quick job skips.

1 · Survey

The stream, its phases, its temperature and pressure range, its hazards and the answer that is wanted are noted, and the sample is chosen to suit them.

2 · Tap

The probe and the tap are placed where the flow is, with a pressure let-down at the tap and a short, small line away from it.

3 · Loop

A fast loop with a filter and a flow indicator keeps the sample fresh and returns the unused part to the process, with a check valve so that nothing runs back.

4 · Close

The cylinder station is filled and purged through closed lines, and the purge goes to the return, to a flare, or to a vent that is led away from people.

5 · Interlock

Three-way valves with interlocked handles make the steps follow one another, so that a mistake costs a restart and not a spill.

6 · Prove

The line is leak-tested, its lag is measured, a sample of known composition is run through it, and the record is handed over with the system.

Which sample, which job

Method	How it works	What to watch
Open grab sample	fills a container at a tap and lets the rest go to the air	quick and cheap, but it exposes the person at the tap, loses the light components and takes in air
Closed cylinder sample (this page)	fills a closed cylinder through closed lines, with a purge, and gives the rest back to the process	needs a purge-compatible cylinder and an order of valves that cannot be got wrong
Online analyser loop (this page)	keeps a fast loop moving and feeds a conditioned sample to an analyser	the lag and any condensation decide whether the reading is of the process
Automatic pipeline sampler	takes small portions in proportion to the flow to build one sample of a whole parcel	a different machine, for transfers of a whole parcel, and not what this page builds

The step people underrate is the lag. A sampling line that is a little too long does not give a slightly worse sample; it gives a sample of a process that has already moved on.

Work content

What the system contains, element by element.

Read it as a checklist: a system missing a row will deliver a sample, but not a true one, and not a safe one.

A sampling point with its fast loop on a plain white studio background: a short horizontal stainless process pipe with flanged ends on grey steel supports, a flanged connection on top carrying a slim probe, a narrow stainless loop rising past an upright stand through a small filter housing and a glass-tube flow meter and returning to the pipe through a ball valve, a pressure gauge turned away from the camera, and a plain pale grey enclosure with a blank closed door beside it, and no people

Fig · 03 — A sampling point and its fast loop: a probe in the process pipe, a narrow loop through a filter and a flow meter back to the pipe, and an enclosure for the conditioning — illustrative render.

Element	What it does	What matters
Probe and tap	take the sample from the stream	reach into the flow, are placed where the stream is moving, and can be isolated and removed safely
Fast loop	keeps the sample fresh	returns the unused part to the process at a lower pressure than the tap, with a check valve so that nothing runs back
Pressure let-down	lowers the pressure at the tap	shortens the delay and shrinks the volume in the line, and does not let a liquid flash
Filter	takes out what would foul the panel	small in volume, kept clean by the flow in the loop, and not a place where old sample can hide
Heating and cooling	keep the sample in the state it was in	heated where the sample must stay above the temperature at which a vapour drops out, and cooled where the stream is hot
Conditioning panel	sets the pressure, the flow and the dryness the analyser needs	a regulator, a filter, a flow meter and needle valves on short, small stainless tubes
Cylinder station	fills a closed cylinder	purged with the stream before it is filled, with a valve at each end and a place to hang the cylinder
Purge and return	take away what is flushed out	to the process, to a return line or to a flare, and never to the room
Valves and interlock	fix the order of the steps	three-way valves that switch gently, with handles that cannot be moved out of order
Instruments	show that the system is doing what it should	a flow indicator, a pressure reading and a temperature reading, read at the places that decide the sample
Frame or enclosure	carries and protects the parts	rigid, with room for the hands, a drip tray, and heat tracing and insulation where the sample needs them
Procedure and record	fix the steps and the proof	the same for every sample, with the sample, the date and the line recorded
Testing & documentation	prove the system first	a leak test, a lag measurement, a run with a sample of known composition, the interlock exercised, and a record the customer can inspect

The elements that decide the result are the tap and the fast loop, and the one that decides whether it stays safe is the interlock. The first two make the sample true, and the third keeps it closed.

Full specification — expand

System	A probe and tap in the live stream; a fast loop with a filter and a flow indicator that returns the unused part to the process; a pressure let-down at the tap; a conditioning panel with a filter, a regulator, a flow meter and heating where the sample must stay above the temperature at which a vapour drops out; a closed cylinder station with a purge and a return; three-way valves with interlocked handles; a frame or an enclosure; a written procedure; a record of each sample; and testing and documentation before handover
The One Idea	Nothing may change on the way.
Why The Sample Is Taken From The Live Stream	A sample from a dead leg or a drain is a sample of what has been standing there; the probe reaches into the stream, and the tap is placed where the flow is, so that the sample is of the process as it is now
Why A Fast Loop	A long line makes a sample old before it arrives; a fast loop keeps the stream moving past the sampling point and returns the unused part to the process, at a lower pressure than the tap so that the loop flows, so that the sample is fresh and nothing is sent to the room
Why The Sample Must Not Change	A cool line can drop a vapour out as a liquid, a pressure drop can flash a liquid into vapour, and a long wall can hold a sticky component back; so the line is short and small, heated where it must stay above the temperature at which a vapour drops out, and held at the pressure that keeps the sample as it was
Why Closed And Purged	Venting a sample to the air exposes whoever is standing there and releases what the process was holding; so the cylinder is purged with the stream and filled through closed lines, and what is flushed out goes back to the process, to a return line or to a flare, never to the room
Standards	ASTM D3700 covers obtaining LPG samples using a floating-piston cylinder, which holds a liquid sample under pressure so that its light components stay in it. This page prints none of its procedures or limits, and no edition year: those come from the standard the customer names. Approval of a system rests with the customer and the authority they name; none is claimed here
Configurations	A closed liquid sampling station, a gas sample conditioning system, and a mobile closed sampling cart
Scope Boundary	This page is the closed sampling system, which takes a true sample of a process stream and brings it to a cylinder or an analyser without releasing it. It is not a gas mixing system, which makes a blend of known gases (see gas mixing system), not a gas purging system, which clears a line or a vessel with an inert gas (see gas purging system) and not an oil purification unit, which cleans and dries an oil (see oil purification unit). It does not analyse the sample, it is not a system for transfers of a whole parcel, and it does not make an area safe for a flammable vapour: that needs a hazardous-area design. No certification or accreditation is claimed here
Status	Neometrix engineers closed sampling systems to order, and no delivered closed sampling system is claimed.

Configurations

One method, three ways to build the system.

The method, the tap, the loop, the closure and the proof are shared. What changes is whether the sample goes to a cylinder or to an analyser, and where the person stands.

Closed liquid sampling station

A cylinder station at the line, filled and purged through closed lines

For a liquid that must not be vented: a tap, a fast loop, a cylinder station for a floating-piston or a double-ended cylinder, and a return, on a frame beside the line.

Gas sample conditioning system

A fast loop and a panel that give an analyser a true gas sample

For an online analyser: a probe, a fast loop, a pressure let-down, a conditioning panel with heating where it is needed, and a return, in an enclosure beside the analyser.

Mobile closed sampling cart

A cylinder station on wheels, joined to a sampling point by closed hoses

For a plant with many sampling points: the cart is wheeled to the point, joined by closed hoses, filled and purged, and the purge goes back to the return at that point.

And the part that is not equipment at all, yet decides all three: the survey and the test plan. They fix the stream, the place of the tap, the lag that can be accepted, the order of the steps and the checks at handover. They are written from the customer's own stream and sampling procedure, not from the panel.

The drawings

A reference set, drawn as real CAD sheets.

Two sheets of one reference configuration: the process and instrument schematic of a closed sampling system, and its general arrangement with three details. They show the tap, the fast loop, the closed cylinder station and its interlock, the conditioning panel, the lag, the order of the steps and the floating-piston cylinder. They carry tags and letters only. Every pressure, temperature, flow, time and size is fixed by design for the customer's stream and sampling procedure.

Reference drawing sheet one, the process and instrument schematic of a closed sampling system. A heat-trace controller sits above a process line. A probe and tap with an isolating valve and a pressure let-down rise from the line into a fast loop that carries a filter and a flow indicator and returns the unused part to the process through a check valve, with a branch to a flare. A closed cylinder station hangs below the loop between two valves whose handles are interlocked, and purges to the return through a check valve. A conditioning panel takes a sample from the loop through an isolating valve, a pressure let-down, a filter and a flow indicator and a heated line with a temperature sensor to an analyser, which returns to the loop. A legend, a table of holds and releases, ten notes and a title block stamped reference configuration, not for construction

Fig · 04 — Sheet 01, the process and instrument schematic: the tap, the fast loop, the closed cylinder station with its interlock, the conditioning panel with its heated line, the analyser and the return. Reference configuration, tags only.

Reference drawing sheet two, the general arrangement and details of a closed sampling system. An elevation of a closed liquid sampling station shows a stainless frame with a back panel, an upright sample cylinder with a valve block at each end and two clamps, a filter, a flow meter, a manifold of three-way valves, a drip tray and bulkhead fittings, with dimension letters for its height and width. An elevation of a mobile cart shows the same kind of cylinder on a frame with castors, joined to a sampling point by two closed hoses with couplings. An item list numbers twelve parts. Detail A compares the lag of a long line with that of a fast loop. Detail B is a table of valve states for purging, filling, isolating and removing the cylinder. Detail C is a section through a floating-piston cylinder with its sample side, piston and pre-charge side. A title block stamped reference configuration, not for construction

Fig · 05 — Sheet 02, the general arrangement and details: the station and the cart in elevation, the lag, the order of the steps and the floating-piston cylinder. Reference configuration, letters only.

Every real system is drawn for its own stream, hazards and site. These sheets are the arrangement and the order of control that a project set starts from. Approval of any drawing rests with the customer and the authority they name; none is claimed here.

PDF · two sheets

Reference drawings — schematic and arrangement

PDF · capability sheet

Closed sampling system — what Neometrix engineers

Where it is used

Wherever a sample has to be taken from a stream, and has to stay true and stay closed.

The common thread is a stream that cannot be let out, a person who has to be kept away from it, and an answer that is only as good as the sample.

Process plants

Where a liquid or a gas has to be sampled from a line without letting any of it out.

Gas supply and gas plants

Where a gas line feeds an analyser, and the reading has to be of the line and not of the sampling tubes.

Storage and transfer points

Where samples are taken from storage vessels and transfer lines, and the person at the tap has to be kept out of the vapour.

Laboratories and quality control

Where a sample has to reach the bench unchanged, and its record has to say where it came from.

Watch

See it in motion.

A short walkthrough video of the closed sampling system.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a closed sampling system actually do?

It takes a sample of a process stream and brings it to a cylinder or to an analyser without letting it out and without changing it. A probe reaches into the stream. A fast loop keeps the sample fresh and gives the unused part back to the process. A conditioning panel sets the pressure, the flow and the dryness the analyser needs, or a cylinder station is purged and filled through closed lines. Interlocked valves fix the order of the steps. It does not decide what a sample is tested for or what limit the answer is held to: those come from the customer's own specification, and the system holds to them.

Q · 02 Why a fast loop, and why not just a long line?

Because the time a sample takes to get from the tap to the analyser or the cylinder is the lag, and the lag makes the answer a record of the past. A long line has a large volume, and the sample in it is old when it arrives. A fast loop keeps the stream moving past the sampling point and returns the unused part to the process, so the sample is taken from fresh flow. The return point is at a lower pressure than the tap, so that the loop flows, and a check valve stops anything running back. Filters and pots slow the answer too, because they hold old sample and mix it with new, so they are kept small and kept in the flow.

Q · 03 Why closed and purged, and not a quick grab sample?

A grab sample is quick, but it lets the rest of the flow out to the air. That exposes whoever is standing at the tap and releases what the process was holding, and it loses the light components of the sample and takes in air. A closed system fills the cylinder through closed lines and purges it with the stream first, so that it holds neither air nor the last sample. What is flushed out goes back to the process, to a return line or to a flare. The purge needs a cylinder that is made to be purged, so that the sample that has been captured is not flushed out with it.

Q · 04 What can change a sample on the way?

Four things. Age: a long line delivers old sample. Phase: a cool line can drop a vapour out as a liquid, and a pressure drop can flash a liquid into vapour, so the sample is no longer what the stream was. The wall: sticky components can be held back by long or large surfaces. And contamination: air, or the last sample, left in a cylinder or a dead leg. The system answers each in turn: a fast loop for age, heating and pressure control for phase, a short small line for the wall, and a purge and a closed fill for contamination.

Q · 05 Is this the same as the gas mixing system, the gas purging system or the oil purification unit?

No, and the differences are worth stating precisely. The gas mixing system page covers making a blend of known gases. The gas purging system page covers clearing a line or a vessel with an inert gas. The oil purification unit page covers cleaning and drying an oil. This page is the closed sampling system, which takes a true sample of a process stream and brings it to a cylinder or an analyser without releasing it. It does not replace any of them, and it does not claim what they claim a second time.

Q · 06 Has Neometrix built one of these?

We would rather answer this plainly than let a page imply otherwise. Neometrix engineers closed sampling systems to order, and no delivered closed sampling system is claimed. What stands behind the offer is adjacent: Neometrix engineers a gas mixing system (see the gas mixing system page), a gas purging system (see the gas purging system page) and an oil purification unit (see the oil purification unit page). The cylinders, valves, regulators, filters, flow meters, heaters and analysers are catalogue items, bought in, not invented. What Neometrix engineers is the system around them: the survey, the probe and tap, the fast loop, the conditioning panel, the cylinder station, the purge and the return, the interlock, the procedure and the record. So the honest position is that the system is engineered to order, the neighbouring disciplines are in the building, and the first system of this exact kind will be built around the customer's own stream rather than taken off a shelf.

Q · 07 Which standard applies, and what can the system not do?

ASTM D3700 covers obtaining LPG samples using a floating-piston cylinder, which holds a liquid sample under pressure so that its light components stay in it. This page prints none of its procedures or limits, and no edition year: those come from the standard the customer names. The system takes a sample, keeps it true and keeps it closed. It does not analyse the sample, it is not a system for transfers of a whole parcel, it does not make an area safe for a flammable vapour, which needs a hazardous-area design, and it does not replace the customer's own sampling procedure: this page claims no certification or accreditation. No pressure, temperature, flow, time, size or quantity figure is printed here, and approval for use rests with the customer and the authority they name; none is claimed here.

Q · 08 What do you need from us to quote?

Six things, and most of them describe your stream rather than the system. First, the stream: what it is, whether it is a liquid, a gas or both, and its range of temperature and pressure. Second, the sample: what is wanted, a cylinder or a feed to an analyser, and how often. Third, the line: where the tap can go, and how far it is from where the sample is used. Fourth, the hazards: whether the stream is flammable, toxic or corrosive, and where the purge may go. Fifth, the supplies: power, heating, and a clean gas for purging. Sixth, the record: what you want kept for each sample. From that we come back with a system concept, a written test plan you can check, and a budgetary price.

The neighbouring pages, and how they differ from this one.

Three neighbours: one makes a blend, one clears a line, one cleans an oil.

↗ A blend

Gas Mixing System

Makes a blend of known gases - where this page takes a true sample of a stream, and may be the way a blend is checked.

↗ A purge

Gas Purging System

Clears a line or a vessel with an inert gas - the same discipline of a closed, ordered purge, aimed at a different job.

↗ An oil

Oil Purification Unit

Cleans and dries an oil - a different job from taking a true sample of it, which is often how an oil is proved.

Browse all Neometrix product lines.

Get a quotation

Tell us the stream,
and the sample you need.

The projects desk replies within two working days with a system concept, a written test plan you can check, and a budgetary quotation. Write to [email protected] or use the form.

Enquire — closed sampling system Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED-TO-ORDER CLASS — CLOSED SAMPLING SYSTEM SURVEY · TAP · LOOP · CLOSE · INTERLOCK · PROVE — NOTHING MAY CHANGE ON THE WAY ENGINEERED IN NOIDA · INDIA