FAQ - Sampling and Systems
Representative sampling is essential for reliable process analysis, product quality and safe plant operation. Below we answer frequently asked questions about the sample coolers, sample cylinders and engineered sampling and sample-conditioning systems supplied by Ingenieursburo Gommer.
A sample cooler is a compact heat exchanger used to reduce the temperature of a hot process sample before it reaches an analyser, sample station or laboratory container. Typical applications include steam, boiler water, condensate and hot process liquids. Cooling protects operators and instruments, helps prevent flashing and brings the sample to a controlled temperature suitable for reliable measurement. View Sample Coolers on the Gommer website.
The process sample normally passes through a coiled tube while cooling water flows around the coil inside an outer shell. The two streams are commonly arranged in counterflow to maximise heat transfer. The sample and cooling water remain physically separated.
Yes. Steam sampling is one of the principal applications for high-pressure sample coolers. The cooler must remove both the latent heat required to condense the steam and the sensible heat required to cool the condensate to the required outlet temperature.
A high-pressure sample cooler is designed for process samples at pressures significantly above normal utility-water pressures. These designs are commonly used in power-generation steam/water cycles, boiler systems and demanding process applications. Specialist manufacturers such as Dr. Thiedig offer coolers for these conditions. View Sample Coolers on the Gommer website.
Correct sizing requires the sample medium, inlet pressure and temperature, sample flow, desired outlet temperature, cooling-water inlet temperature, cooling-water pressure and available cooling-water flow. A heat balance is then used to determine the required cooling duty.
There is no universal cooling-water flow. The requirement depends on the heat load from the sample and the permitted rise in cooling-water temperature. Ingenieursburo Gommer can calculate the required cooling-water demand for a specific application.
The achievable outlet temperature depends on cooler area, sample flow, cooling-water flow and the available temperature difference. A correctly sized counterflow cooler can approach the cooling-water inlet temperature, but an appropriate temperature approach must always be allowed for.
A higher cooling-water inlet temperature reduces the available temperature difference and therefore cooling capacity. For critical applications, sizing should use the highest realistic cooling-water inlet temperature rather than the annual average.
316 and 316L stainless steel are widely used. Depending on process and manufacturer, alternatives can include Monel, Hastelloy, Inconel, Duplex, Super Duplex and selected nickel alloys. Incoloy may also be considered for specific high-temperature or corrosive applications where available.
Periodically check the cooling-water side for scale, deposits and fouling. Also check connections, sample outlet temperature and the process coil for leakage. A cooling-water strainer and appropriate water treatment can significantly reduce fouling.
A sample cylinder is a pressure-rated container used to collect, transport and store a representative gas or liquid sample while maintaining the required sample conditions. Typical applications include natural gas, LPG, NGL, refinery products, speciality gases, hydrogen and process chemicals. View Sample Cylinders on the Gommer website.
Sampling cylinders are available from small analytical volumes to several litres. Common industrial capacities include approximately 75, 150, 300, 500, 1,000 and 2,250 ml, with other sizes available depending on manufacturer and design.
The cylinder working pressure must exceed the maximum pressure to which it can be exposed during filling, transport and use. Many general-purpose cylinders are available around the 1,800 psi / 124 bar class, while selected designs are available for considerably higher pressures.
A single-ended cylinder has one process connection. A double-ended cylinder has a connection at both ends, allowing process fluid to flow through the cylinder during purging. Flow-through purging can greatly reduce residual gas and contamination.
A floating-piston cylinder contains a movable piston separating the process sample from a displacement gas. Pressure on the opposite side helps maintain the sample at pressure during collection and handling, reducing the risk of phase change.
Typical applications include LPG, NGL, volatile hydrocarbons, crude-oil samples and other pressurised liquids where phase change could alter composition.
An outage tube limits the amount of liquid that can enter a cylinder, leaving a defined vapour or expansion space so thermal expansion cannot hydraulically fill and overpressure the cylinder.
Common configurations use needle or ball valves. Depending on the application, assemblies may also include rupture discs, relief devices, quick couplings, outage tubes, pressure gauges, handles and protective frames. HOKE sample cylinders can be configured with associated instrumentation valves and fittings.
The correct cylinder depends on the required sampling method. A flow-through double-ended cylinder may be appropriate for some procedures, while a constant-pressure floating-piston cylinder may be preferable where maintaining a single liquid phase is essential.
Yes, provided the complete cylinder assembly is suitable for the required hydrogen pressure, purity and service conditions. Material compatibility, valves, seals, cleanliness and connection design must all be considered.
Special inert surface treatments can be beneficial for trace sulphur, H2S, moisture, VOCs and speciality or high-purity gases where components could adsorb onto untreated metal surfaces.
Cleaning requirements depend strongly on the service and may include flushing, solvent cleaning, drying, evacuation, inert-gas purging or manufacturer-defined cleaning processes.
A sample conditioning system prepares a process sample so an analyser receives it at the correct pressure, temperature, flow and phase. It may combine isolation, filtration, pressure reduction, cooling, heating or vaporisation, flow control and safe venting or return. View Sampling and Systems on the Gommer website.
A sampling system covers the complete path from process extraction to final collection or analysis. Sample conditioning specifically refers to the equipment used to modify sample conditions before analysis.
A grab sample station allows an operator to manually collect a representative process sample in a bottle or cylinder while controlling pressure, flow, purging, isolation and depressurisation.
In a closed-loop system, purge or bypass flow is returned to the process or routed to a designated recovery, flare or disposal system rather than being openly discharged. This can reduce emissions and operator exposure.
A fast loop moves process fluid rapidly from the main process line past the sampling point or analyser system. Only a small side stream enters the analytical conditioning system, reducing sample transport delay.
Transport lag is the time taken for a process change to travel from the extraction point to the analyser. Long small-bore lines, large internal volumes and low sample flows can create significant delays.
The sample temperature must remain safely above the dew point of components that must stay in the gas phase. Heated sample lines, heated regulators, controlled pressure reduction and insulated enclosures can be used where required.
Pressure and temperature must be controlled so the liquid remains above its vapour-pressure requirement throughout the sampling path. Excessive pressure drop can cause lighter components to evaporate.
316/316L stainless steel is the normal starting point. Depending on corrosion, purity and temperature requirements, alternatives can include Monel, Hastelloy, Inconel, Duplex, Super Duplex, PTFE, PFA and selected specialised alloys.
Depending on the application, systems can combine Dr. Thiedig sample coolers, HOKE valves and sample cylinders, Gyrolok tube fittings, GO Regulator, TESCOM and Veriflo pressure-control products, Headline filtration components and Malema flow equipment.
Typical industries include power generation, oil and gas, refining, petrochemical, chemical processing, hydrogen, semiconductor, laboratories and analytical systems.
Depending on project and components, documentation can include EN 10204 material certificates, certificates of conformity, pressure-test reports, drawings, P&IDs, bills of material, manufacturer datasheets and inspection and test documentation.
Provide the process medium, pressure, temperature, sample flow, required outlet conditions and analytical objective. Ingenieursburo Gommer can support projects from an individual sample cylinder or cooler through to a complete engineered sampling panel. View Contact and Engineering Support on the Gommer website.