Sampler flushing

Salinity of seawater captured by various sampling devices in the CEPEX enclosure indicates problems not revealed in the usual oceanographic sampling situation. Relative to peristaltic pumping, all samples exhibited some salinity anomalies. Inadequate flushing to rinse the sampler of any concentrated brine or entrapped seawater is thought to be a problem. 

In our study, contact of the anoxic samples with oxygen was avoided. The samples were transferred from the samplers (Go-Flo, General Oceanics, 5 L) into bottles equipped with three-way taps under N2 pressure. The bottles had previously been flushed with N2, and they were completely filled. Filtration in the laboratory with acid-cleaned 0.45- xm cellulose nitrate filters (Sartorius) and a polycarbonate filtration unit (Sartorius) was also carried out under nitrogen gas. Most analytical determinations were performed in the laboratory on the sampling day. 

Be sure samples are consistent. For fixed volume sample loop, use 2-3 times loop volume to ensure loop is completely filled. Be sure automatic sampler vials contain sufficient sample. Check syringe-type injectors for air. In systems with wash or flushing step, be sure wash solution does not precipitate sample components. 

Procedure Formaldehyde sample from the sampler was injected into the carrier stream where it was mixed with pararosaniline and then sulfite to form an alkylsulfonic acid chromophore which can be monitored spectrophotometrically at 570 nm For calibration, standard formaldehydes were sequentially introduced after a stable baseline was obtained At least five consecutively reproducible peaks were recorded for each concentration After each study or each day of operation, the FIA system was cleaned to remove any pararosaniline film, alkylsulfonic acid colored product, or particulate matters This reduced the scattered light in the absorption cell and the staining of the tubing walls. The clean-up procedure was initiated by running distilled deionized water through the system for five minutes followed by another five minutes washing with 0 1 N nitric acid and then flushing the unit for 30 minutes with deionized water The chromotropic acid method was used for comparative studies, and the analytical procedure for the chromotropic acid method was based on the procedure recommended by the American Public Health Association (12) ... 

Non-flushing samplers employ a suction effect for sampling. This is caused by a pressure difference between the device chamber and water... 

The random d time sample (RDT) has to be taken at a random time during office hours, avoiding the periods of frequent water use (breakfast, limch and dinner) and the period of overnight stagnation. A professional sampler collects a 1-litre sample, without flushing the tap. 

The sampler has to estimate the plumbing system volume. The fully flushed (FF) sample is taken after flushing three pipe volumes or 5 minutes (if the plumbing dimensions are not known) at 5 litres/minute. The sampler eollects a 1-litre sample. 

O.Spl of liquid cumene was injected into an injector port heated to 300°C and flushed with 20ml/min Ar. For the sorption studies of benzene, 150 pi of vapoiu was injected. The effluent gas was analysed with an automated rotating Multi-Ampoule-Sampler system (MAS), where pre-evacuated ampoules were broken, sealed and later analysed in a GC. The fastest sampling... 

The use of Nansen bottles has some disadvantages, one being based on their construction. The closing mechanism impairs flushing of the sampler due to dead volumes and turbulent mixing. Modern samplers of the Nansen type are usually made of plastic materials such as polycarbonate (PC) and poly (vinyl chloride) (PVC) instead of brass (Table 1-2). Such samplers are less robust, but lighter, they are non-corrosive, greasing of the valves becomes unnecessary and interference with sample composition is minimized. 

TPN transparent plastic Nansen water sampler, PC tube. Teflon O-rings, ball valve, reduced flushing 1.7 3 ul Std., (TM) HB... 

GO-FLO PVC tube. Teflon coating optional, external rubber spring, for single use and in rosette-type samplers, COC, reduced flushing 1.7-100 3.9 7 ul Std., TM GO... 

LVWS large volume water sampler, stainless steel, internal reversing thermometers, partition wall in the middle part, one opening with deflector plate, poor flushing characteristics 270,400 130, 220 ul (TO) HB... 

As a rule, subsampling for the determination of dissolved oxygen should be carried out as soon as possible after the sampler has been recovered. The bottles are unstoppered and after flushing the nozzle of the hydrocast sampler with sample water, the end of the nozzle tube is inserted into the sample bottle almost to the bottom. The nozzle should be transparent and sufficiently narrow to ensure that the sample stream carries with it any air bubbles and the air segment in the tube but wide enough to fill the bottle rapidly. 

Plastic samplers are cleaned internally in a manner similar to that described for plastic bottles. Go-Flo samplers (Niskin type see Qiapter 1) are first thoroughly cleaned with a detergent, then rinsed with tap water and, after soaking in about 1 mol/L HQ (a.g.) for several days, flushed with a final rinse of purest distilled water. Afterwards, the samplers are wrapped in clean plastic bags for storage. 

From the pipeline during discharging or loading. Pipeline samples may te taken either manually or with an automatic sampler. If the pipdine requires displacement or flushing, exercise care that the pipeline sample includes the entire cargo and none of the displacement Separate samples may be required to cover the effect of the line displacement on the prior or following transfer. 

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