manual sampling of no pressurised tanks
Post on 03-Jun-2018
223 Views
Preview:
TRANSCRIPT
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 1/21
Human DevelopmenConsultants Ltd.
Training Module
Manually Sample
Non-PressurizedTanks
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 2/21
Manually Sample
Non-Pressur ized Tanks
December, 2003
Human Development Consultants Ltd.
© HDC Human Development Consultants Ltd.
All rights reserved . No part of this publication may be copied, reproduced, stored in a computer orretrieval system, published, distributed, or transmitted in any form or by any means whatsoever, including
without limitation by mechanical means, photo copying, recording, digital or electronic media, the Internet,or otherwise, without the express prior written permission of HDC Human Development Consultants Ltd.(HDC). HDC grants to the purchaser of a Single User License (as defined in the agreement with suchpurchaser) a limited license to store the electronic file(s) on one computer only and to make a singlepaper copy of this publication. HDC grants to the purchaser of a Site License (as defined in theagreement with such purchaser) a limited license to store the electronic file(s) on one local area networkserver accessible by individual users' computers at one site or location only and to make paper copies ofthis publication for a company’s employees at the same site or location only. Each site or location mustpurchase a separate Site License for employees at that site. HDC grants the purchaser of a CorporateLicense (as defined in the agreement with such purchaser) a limited license to store the electronic file(s)on its intranet and on computers at company sites or locations and to make paper copies for any or allemployees. Nothing in the foregoing restricts, amends or abrogates the provisions of the agreementbetween HDC and the purchaser of the applicable license. Any copying or use other than pursuant tosuch a license is illegal. For further information, please consult the applicable license agreement.
This publication is designed to provide general information regarding the subject matter covered. Carehas been taken to ensure the accuracy of the information and that the instructions contained in thispublication are clear and reflect sound practice. The user understands that HDC is not providingengineering services. The user understands that any procedures (task steps) that are published orreferenced may have to be modified to comply with specific equipment, work conditions, companystandards, company policies and practices, legislation, and user qualifications. HDC does not make anyrepresentations, guarantees, or warranties of any kind whatsoever with respect to the content hereof andthe results to be achieved by implementing the procedures (task steps) herein. To the maximum extentpermitted by applicable law, in no event shall HDC be liable for any damages whatsoever (includingwithout limitation, direct or indirect damages for personal injury, damages to the environment, damages tobusiness property, loss of business profit, or any other pecuniary loss). The use of the information andprocedures (task steps) herein is undertaken at the sole risk of the user.
ISBN 1-55338-038-X
Canadian Cataloguing in Publication Data
1. Petroleum—Sampling. I. HDC Human Development ConsultantsTP692.5.M25 2003 665.5’028’7 C2003-905958-8
This training kit consists of the following parts:
♦ Training Module and Self-Check♦ Knowledge Check and Answer Key♦
Blank Answer Sheet
♦ Performance Check ♦ Job Aid
Published by HDC Human Development Consultants Ltd.
Published in Canada
HDC Human Development Consultants Ltd.
Website: www.hdc.ca
E-mail: marketing@hdc.ca
Phone: (780) 463-3909
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 3/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
ContentsTraining Objectives 1
1 Introduction 1
2 Samples 3
2.1 Spot and Composite Samples 3
2.2 Sampling Levels 4x
3 Sampling Equipment 7
3.1 Samplers (Primary Sample Receiver) 8
3.2 Drop Cords and Trip Cords 14
3.3 Sample Containers (Secondary Sample Receiver) 15
3.4 Sampler and Sample Container Closures 15
4 Sample Accuracy 16
4.1 Uncontaminated Sample 16
4.2 Representative Sample 17
4.3 Sample for Laboratory Analysis 19
4.4 Properly Labeled Sample 19
4.5 Correct Sample Handling and Shipping 20
5 Safety 21
5.1 Physical Hazards 21
5.2 Chemical Hazards 22
5.3 Safety before Climbing to the Roof 24
5.4 Safety while Sampling 24
5.5 Sampling Tanks with Floating Roofs 25
December, 2003 Page i of ii
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 4/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
Contents (continued)
6
Sampling Procedures 26
6.1 Spot Sample Procedure: Core Thief Sampler 26
6.2 Spot Sample Procedure: Bacon Bomb Sampler 28
6.3 Spot Sample Procedure: Cage and Bottle Sampler 29
6.4 Spot Sample Procedure: Weighted Beaker Sampler 30
6.5 Running Sample Procedure: Cage and Bottle Sampler 31
6.6 Bottom Sample Procedure: Core Thief Sampler 32
7 Self-Check 33
8 Self-Check Answer Key 37
December, 2003 Page ii of ii
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 5/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
Training
Objectives
Upon completion of this training kit, you will be able to:
Describe the purpose and importance of manually
sampling non-pressurized tanks
Describe types of samples
Describe tank sampling equipment
Describe tank sampling accuracy
Describe tank sampling safety hazards and precautions
Sample tanks
1 IntroductionIn the oil and gas industry, well emulsions, fuel, field chemicals,
by-products from gas processing, and refined petroleumproducts are stored and transported in non-pressurized tanks.
Non-pressurized tanks include storage tanks at well sites,
batteries, plants, and terminals, and also rail tank cars, tanker
trucks, and ship and barge tanks.
Products in a tank are sampled and analyzed to determine the
product’s chemical and physical properties, such as density
(API gravity), water content, and contaminants. These
properties are used in the determination of standard volumes
and prices.
To take a sample, an operator lowers a sampler on a cord from
the gauge hatch at the top of the tank until the sampler is at the
desired level in the tank. At the desired level, the operator
remotely trips the sampler to allow the sampler to fill and then
pulls the sampler back up. The operator carefully transfers the
sample from the sampler to a sample container, closes the
container, and affixes a label to the container. Depending on
the analyses required, the operator analyzes the sample
immediately, takes the sample to a local laboratory, or sends
the sample to a central laboratory.
Tanks are sampled in accordance with the standard practice
published by:
American Petroleum Institute (API): Manual of Petroleum
Measurement Standards, Chapter 8—Sampling; 8.1—
Manual Sampling of Petroleum and Petroleum Products;
8.3—Mixing and Handling of Liquid Samples of Petroleum
and Petroleum Products
December, 2003 Page 1 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 6/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
American Society for Testing and Materials (ASTM):
D 4057-95 (2000)—Standard Practice for Manual Sampling
of Petroleum and Petroleum Products
International Organization for Standardization (ISO):Petroleum Liquids – Manual Sampling (ISO 3170)
Contents of this Training Kit
This training kit describes how to safely and reliably take
manual samples of liquid petroleum products and free water
from non-pressurized tanks. The kit focuses on methods for
sampling:
crude petroleum
liquid hydrocarbons with Reid Vapor Pressure (RVP) below
101.32 kilopascals (kPa) (14.7 pounds per square inch
absolute—psia)
NOTE
Reid Vapor Pressure is the pressure of a liquid when it is
heated to a temperature of 37.8°C (100°F) in a sealed Reid test
chamber. A product’s RVP is a measure of the product’s
volatility: the higher the RVP, the more volatile the product.
This kit is aimed primarily at pipeline terminal/field operators
who are responsible for manually sampling storage tanks, rail
tank cars, tank trucks, and ship and barge tanks. The kitdescribes:
different types of sample
manual sampling equipment
practices which ensure sample accuracy
manual sampling safety issues
procedures for manually obtaining a sample of liquid
hydrocarbons from storage tanks, rail tank cars, tank trucks,
and ship and barge tanks.
This training kit does not include procedures for:
manual sampling of tank residues, lumpy solids, greases, or
asphaltic materials
manual sampling of pipelines
automatic sampling of tanks or pipelines
sampling fuels for determining the fuel’s volatility
sampling products with Reid Vapor Pressure above 101.32
kPa (14.7 psia)
December, 2003 Page 2 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 7/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
This kit is one of a series of two HDC training kits related to
storage tanks. The other kit is Manually Gauge Non-
Pressurized Above-Ground Tanks.
NOTE
This kit provides instruction on tank sampling equipment and its
application. The kit does not endorse or promote any specific
model, manufacturer, or supplier.
2 SamplesThis section describes spot and composite samples and the
levels in the tank at which samples are taken.
2.1 Spot and Composite Samples
Types of sample include:
spot sample—a sample taken at a specific location in a
tank
composite sample—a sample obtained by combining spot
samples in defined proportions so that the sample is
representative of the product in the tank:
– for upright cylindrical tanks, spot samples are taken at
the levels indicated in the following table and blended in
equal proportions. (Sampling levels are described in thenext section.)
Composite Sample: Vertical Cylindrical Tanks
Required SamplesTank Capacity Product Height
upper middle lower
larger than 160 m3 (1000 bbls)
> 4.5 m (>15 ft.)
larger than 160 m3 (1000 bbls)
3 – 4.5 m(10 – 15 ft.)
up to and including
160 m3 (1000 bbls)
December, 2003 Page 3 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 8/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
– for horizontal cylindrical tanks, such as rail tank cars
and tank trucks, samples are taken and blended at the
levels and proportions indicated in the following table.
Figure 1 illustrates this concept.
Composite Sample: Horizontal Cylindrical Tanks
Sampling Level
(percentage of diameter
above the bottom)
Composite Sample
(proportional parts
out of 10)
Liquid Depth
(percentage of
diameter)
upper middle lower upper middle lower
100 80 50 20 3 4 390* 75 50 20 3 4 3
80 70 50 20 2 5 3
70 50 20 6 460* 50 20 5 5
50 40 20 4 6
40* 20 10
30 15 10
20 10 1010 5 10
*Refer to Figure 1.
For tankers or vessels with compartments, take at least one
sample from each compartment. When a composite sample of
the different compartments is required, the volume of sample
from each compartment making up the composite sample
should be in the same proportion as the volume of product in
each compartment. For example, one compartment of a tanker
truck is 100% full and the other compartment is only 60% full.
The composite sample would contain 10 parts from the first
compartment and 6 parts from the second compartment.
2.2 Sampling Levels
Samples are taken from the gauge (thief) hatch at the top of thetank.
NOTE
Samples are not taken from valves near the bottom of the tank.
Such samples are usually not representative of the product in
the tank. Also, with infrequent use, the valve may fail when
opened and tank contents may be spilled.
December, 2003 Page 4 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 9/21
Manually Sample
Non-Pressurized Tanks
December, 2003 Page 5 of 37
Human DevelopmentConsultants Ltd.
50 %
3
3
4
25 %20% level
50% level
75% level 75 %
100%
0%
Tank 90% full
5
5
20% level
50% level
Tank 60% full
10
20% level
Tank 40% full
50 %
25 %
75 %
100%
0%
50 %
25 %
75 %
100%
0%
Figure 1—Sampling Levels and Composite Samples for Horizontal Cylindrical Tanks
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 10/21
Manually Sample
Non-Pressurized Tanks
December, 2003 Page 6 of 37
Human DevelopmentConsultants Ltd.
water & sediment
outlet (suction level)sample
lower 1/3
middle 1/3
lower sample(middle of lower 1/3)
middle sample(middle of middle 1/3)
upper sample(middle of upper 1/3)
(1/6 from top surface)
top sample150 mm (6 in)below surface
bottom sample
upper 1/3
Figure 2—Sampling Levels
The following sampling levels are illustrated in Figure 2:
top sample—a spot sample taken 150 mm (6 in.) below thetop surface of the liquid.
upper sample—a spot sample taken from the middle of the
upper one-third of the product in the tank (i.e., one-sixth of
the depth of liquid below the top surface), excluding any
free water or sediment at the bottom of the tank.
middle sample—a spot sample taken from the middle of
the middle one-third of the product in the tank (i.e., one-half
of the depth of liquid below the top surface), excluding any
free water or sediment at the bottom of the tank.
lower sample—a spot sample taken from the middle of thelower one-third of the product in the tank (i.e., five-sixths of
the depth of liquid below the top surface), excluding any
free water or sediment at the bottom of the tank.
outlet (suction-level) sample—a spot sample taken at the
tank outlet. The opening of the sampler is level with the
bottom of the outlet.
Gauge (Thief) Hatch
Small cover located onthe top of the tank. Thegauge hatch allowsoperators to look insidethe tank and to gauge andsample the tank.
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 11/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
bottom sample—a spot sample taken from the material at
or close to the bottom of the tank. Bottom sample locations
must be specified (e.g., “150 mm [6 in.] from the bottom”).
bottom water sample—a spot sample of the layer of freewater located below the petroleum in the tank
all-levels sample—a sample obtained with a sampler
which is filled to between 70 and 85% while the sampler
passes through the total liquid height in either a downward
or an upward direction:
– an empty, stoppered sampler is lowered to the bottom of
the tank (or just above the free water level). At the
bottom, the stopper is removed remotely and the
unstoppered sampler is raised to the surface at a rate
that allows the sampler to fill between 70 and 85 percent.
– an empty, unstoppered sampler is lowered to the bottom
of the tank (or just above the free water level) at a rate
that allows the sampler to fill between 70 and 85
percent. At the bottom, the stopper is inserted remotely
and the stoppered sampler is raised to the surface.
running sample—a sample obtained with a sampler which
is slowly filled while the sampler passes through the total
liquid height in both downward and upward directions. An
empty sampler, stoppered with a perforated stopper, is
lowered to the bottom of the liquid in the tank and raised to
the surface at a uniform rate that allows the sampler to fillbetween 70 and 85 percent.
3 Sampling EquipmentSampling equipment includes:
samplers (primary sample receiver)drop cords and trip cordssample containers (secondary sample receiver)closures
sample carriers
3.1 Samplers (Primary Sample Receiver)
Several different types of samplers have been designed for
manually sampling petroleum tanks.
December, 2003 Page 7 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 12/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
The type of sampler to use depends on the type of product and
the type of sample required. Before selecting a sampler,
consider the following:
Samplers must be resistant to the solvent action of theproduct and cleaning agents used to clean the sampler after
use.
Plastic samplers and bottles:
– are acceptable for sampling and storing gas oil, diesel
oil, fuel oil, and lubricating oil
– should not be used to store crude oil, gasoline, aviation
jet fuel, kerosene, and white spirit
NOTE
Conventional polyethylene (i.e., non-linear polyethylene)
containers must not be used because the polyethylene may
contaminate the petroleum sample.
Samplers and sample containers must be made of a non-sparking material.
The sample taken must be suitable for the analyses that willbe performed on the sample:
– Samplers must be large enough to contain the requiredsample. If the sampler is used as both primary andsecondary receiver (i.e., if the sample will not betransferred from the sampler to a sample container),samplers must have room for thermal expansion
(approximately 10 to 15%). – Samples may lose light ends (i.e., volatile gases) during
transfer from a primary sampler to a secondary samplecontainer. When analyses of density or composition arerequired, samples should be left in the primary sampleruntil the moment of analysis (providing the primarysampler can be adequately sealed). When takingcomposite samples for density analysis, you will needenough samplers to take the required samples and holdthe samples until the analyses are performed.
Light EndsThe lighter molecules in ahydrocarbon mixture.Light ends have a lowerboiling point and tend tovaporize readily.
– If the sample needs to be mixed before analysis,consider how suitable the sampler is for mixing. Forexample, if a sample of crude oil has stratified in thesampler before arriving at the laboratory, the sampler/sample may need to be placed on a mixer and mixedbefore analysis. In this case, the sampler must be ableto fit on the mixer and withstand the mixing action.
December, 2003 Page 8 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 13/21
Manually Sample
Non-Pressurized Tanks
December, 2003 Page 9 of 37
Human DevelopmentConsultants Ltd.
This section describes:
the four common types of sampler:
– core thief
– Bacon bomb – cage and bottle
– weighted beaker
samplers used for:
– all-levels and running samples
– bottom samples
Core Thief Sampler
Core thief samplers (thiefs) (Figure 3) are used to take spot
samples and bottom samples in storage tanks, rail tank cars,
tank trucks, and ship and barge tanks.
Core thiefs have the following features: a transparent glass or plastic (or metal) barrel with top and
bottom spring-loaded closures
a gauge for determining the height of sediment and water in
the barrel
a mechanical device and trip cord for tripping the valve
closure mechanism. The operator uses the trip cord to
remotely open/close the valve.
Figure 3—Two Core ThiefSamplers(Courtesy of W. L. Walker Co., Inc.)
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 14/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
low clearance: able to take a sample within 15 to 25 mm
(1/2 to 1 in.) of the tank bottom
sufficient weight so that the thief can sink in the product
removable extension rods (from 75 to 460 mm) (3 to 18 in.)for sampling at specific heights above the tank bottom
Samples taken in core thiefs usually have to be transferred to a
sample container so that the thief can be reused.
Bacon Bomb Sampler
Bacon bomb samplers (Figure 4) are used to take bottom
samples and spot samples in storage tanks, rail tank cars, tank
trucks, and in ship and barge tanks.
Figure 4—Two Bacon Bombs(Courtesy of Koehler InstrumentCompany, Inc.)
Bacon bombs have the following features:
a chrome-plated brass or stainless steel barrel
an internal plunger-type valve:
– The plunger opens automatically when the sampler
strikes the tank bottom and closes when the sampler is
raised.
– If the plunger is fitted with a trip cord, the operator can
remotely open and close the plunger by lifting and
releasing the trip cord.
December, 2003 Page 10 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 15/21
Manually Sample
Non-Pressurized Tanks
December, 2003 Page 11 of 37
Human DevelopmentConsultants Ltd.
low clearance: able to take a sample within 15 to 25 mm
(1/2 to 1 in.) of the tank bottom
sufficient weight so that the bomb can sink in the product
removable extension rods (from 75 to 460 mm) (3 to 18 in.)for sampling at specific heights above the tank bottom
Samples taken in Bacon bombs usually have to be transferred
to a sample container so that the Bacon bomb can be reused.
Cage and Bottle Sampler
Cage and bottle samplers (also known as weighted bottle
samplers) (Figure 5) are used for taking spot samples,
all-levels, and running samples, and for taking samples of
volatile products in storage tanks, rail tank cars, tank trucks,and ship and barge tanks.
Cage and bottle samplers have the following features:
a brass, stainless steel, or plastic frame or cage fitted with a
litre or half litre (quart or pint) clear or amber glass bottle
a stopper connected to the cage by a rod (as in Figure 5), a
cord, or a chain. During sampling, the operator removes the
stopper by sharply jerking the drop cord.
sufficient weight so that the sampler can sink in the product
Figure 5—Cage and Bottle Sampler(Courtesy of HERMetic, Inc.)
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 16/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
Samples taken in cage and bottle samplers do not have to be
transferred to a sample container. Bottles can be removed from
the cage, wiped off, stoppered, and transported to the lab. In
this way, volatile light ends are not lost through evaporationduring the transfer. For this reason, cage and bottle samplers
are preferred for sampling volatile products.
Weighted Beaker Samplers
Weighted beaker samplers (also known as weighted can
samplers) (Figure 6) are used for taking spot samples, all levels
samples, and running average samples in storage tanks, rail
tank cars, tank trucks, and ship and barge tanks.
Figure 6—Weighted BeakerSampler(Courtesy of Koehler InstrumentCompany, Inc.)
December, 2003 Page 12 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 17/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
Weighted beaker samplers have the following features:
made of stainless steel, copper, or brass attached to a lead
base
equipped with a stopper tied to the beaker. Duringsampling, the operator removes the stopper by sharply
jerking the drop cord.
sufficient weight so that the sampler can sink in the product
After the sampler has been raised to the surface, the sample
must be transferred to a sample container so that the weighted
beaker can be reused.
The flux used during the soldering manufacture of can
samplers must be thoroughly removed before the sampler can
be used. Some fluxes are difficult to remove and may
contaminate the sample for certain analyses. Check with your
vendor and laboratory to determine the suitability of the
sampler.
Samplers Used for All-Levels and Running Samples
Cage and bottle samplers and weighted beaker samplers
can be used to take all-levels samples and running samples.
Bottles and beakers can be fitted with closures that have small
openings, allowing restrictive filling. When the sampler is
lowered to the bottom of the tank and raised at a uniform rate,
liquid flows into the restrictive opening. The product viscosity,
density, and tank height dictate the size of the opening
required. When the opening size and sampling speed are
correct, a pocket of air remains when the sampler is removed
from the tank. If there is no pocket of air, the sampler filled
before the complete run was completed and the sample may
not be representative of the product at all levels. Even when
filled correctly (i.e., 70 to 85% full), the sample is not
necessarily representative, depending on operator skill and
tank dimensions.
Bacon bomb samplers can be equipped with a needle valve
at the top of the bomb. When the sampler is lowered to the
bottom of the tank at a uniform rate, liquid flows into the lower
end of the sampler only at the rate the air is displaced through
the needle valve at the top.
December, 2003 Page 13 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 18/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
Because you cannot see into the sampler, it is not possible to
determine if the sampler is correctly filled (i.e., if there is a
pocket of air).
Samplers Used for Bottom Samples
Core thief samplers and Bacon bomb samplers are used for
bottom sampling. Both types allow a sample to be taken from
very close (15 to 25 mm; 1/2 to 1 in.) to the bottom.
The core thief sampler is open while being lowered to the tank
bottom: product flows through the sampler. When the sampler
strikes the bottom (or when the operator remotely trips the
mechanism), the valves close, trapping bottom product.
The Bacon bomb sampler is closed while being lowered to the
tank bottom. When the sampler strikes the bottom, the valve
opens, admitting product into the bottom and expelling air from
the top. When the sampler starts moving upward, the valve
closes and traps bottom product.
3.2 Drop Cords and Trip Cords
Drop cords or chains (also known as sample lines or lowering
cords) are used to lower the sampler into the product. Trip
cords (also known as plunger lines or valve cords) are used totrip the valve mechanism on core thief and Bacon bomb
samplers.
Cords and chains should be spark resistant (i.e., unable to
carry a static electrical charge—a source of ignition). For this
reason, cords are usually made of vegetable fibers such as
cotton or sisal; man-made fiber content should be limited.
Chains are usually made of nickel-plated brass or stainless
steel.
Before taking samples, the operator measures and marks the
required sample levels on the cord or chain. Cords are
available with brass ferrules spaced at 300, 400, or 450 mm
(12, 16, or 18 in.) intervals from the bottom of the sampler.
December, 2003 Page 14 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 19/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
3.3 Sample Containers (Secondary Sample Receiver)
Sample containers (secondary sample receivers) are normally
clear or amber glass or metal bottles with an adequate stopper.
Bottles normally range between 0.25 and 5 litres (1 cup to
1 gallon); they must be large enough to hold the required
sample with sufficient space for expansion and mixing
(10 to 15%).
As with samplers:
sample containers must be resistant to the solvent action of
the product and cleaning agent
conventional polyethylene (i.e., non-linear polyethylene)
containers must not be used
sample containers must be made of a non-sparking material
Sample containers must have a tight stopper to prevent the
escape of volatile light ends.
On metal bottles, the flux used during the soldering
manufacture must be thoroughly removed before the bottle can
be used. Some fluxes are difficult to remove and may
contaminate the sample for certain analyses. Check with your
vendor and laboratory to determine the suitability of the metal
bottle.
3.4 Sampler and Sample Container Closures
Closures for samplers and sample containers are corks, inert
plastic stoppers, ground glass stoppers, and plastic or metal
screw-caps.
Corks should be clean, intact, and free from crumbling or loose
bits. Corks:
should only be used for one type of product to prevent
cross-contamination between different types of productshould not be used for volatile liquids, because the vapor
can diffuse into the cork and contaminate other samples
December, 2003 Page 15 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 20/21
Manually Sample
Non-Pressurized Tanks
Human DevelopmentConsultants Ltd.
Wrapping the cork in clean aluminum foil before insertion into
the container prevents the sample from contacting and
contaminating the cork. Wrapping any stopper with aluminum
foil protects highly refined products from moisture and dust.Containers with screw caps are used for samples that will be
tested for density or composition. Screw caps must provide a
vapor-tight seal. Caps should be fitted with a liner made of cork
or other oil-resistant material. Cork liners must be replaced
each time the screw cap is used to prevent cross-contamination
between samples.
Rubber stoppers should not be used because the rubber may
be degraded by the product.
4 Sample AccuracySamples must be taken and handled properly to ensure the
sample which arrives at the laboratory is representative of the
product in the tank. If sampling techniques are not correct, the
sample—and subsequent analyses—may not be accurate.
Inaccurate test results can mean lost revenue for your
company. Sampling must therefore be carefully carried out.
Ensure that:
the sampler and sample container are free of contaminants
the sample is representative of the product (i.e., has the
same composition as the product)
the sample is suitable for the required laboratory test
the sample is correctly labeled
the sample is correctly handled and transported
4.1 Uncontaminated Sample
Cleanliness is an important part of proper sampling: any
contaminants (such as water, dirt, cleaning solvent, soap, lint)
introduced into the sample will produce inaccurate test results. All sampling equipment must be clean before a sample is
taken.
December, 2003 Page 16 of 37
8/12/2019 Manual sampling of no pressurised tanks
http://slidepdf.com/reader/full/manual-sampling-of-no-pressurised-tanks 21/21
Manually Sample
Non-Pressur ized TanksHuman Development Consultants Ltd.
Cleaning Procedure
After the sample has been removed, reusable samplers and
sample containers should be cleaned thoroughly with cleaning
solvent to remove all traces of product and sediment.
WARNING
Read the material safety data sheet (MSDS) for the cleaning
solvent. Use the personal protective equipment recommended
in the MSDS when working with the solvent. Discard the
solvent in accordance with your company’s hazardous waste
procedures.
Cleaning with solvent is followed by a wash in a strong soap
solution to remove all traces of solvent, a thorough rinse with
tap water, and a final rinse with distilled water. The containersmust be air dried, either with clean, warm pressurized air or in a
hot dust-free cabinet. As soon as the containers are dry, they
must be stoppered and stored in a clean cabinet.
Gauge (Thief) Hatch
Dirt and grime may be present around the tank’s gauge hatch.
Operators should ensure that the gauge hatch and the area
End of Sample A full licensed copy of this kit includes:
• Training Module and Self-Check
• Knowledge Check and Answer Key
• Blank Answer Sheet
• Performance Check
• Job Aid
top related