ASTM F1778-97
(Guide)Standard Guide for Selection of Skimmers for Oil-Spill Response
Standard Guide for Selection of Skimmers for Oil-Spill Response
SCOPE
1.1 This guide covers considerations for selecting skimmer systems for the recovery of marine-oil spills. The purpose of this guide is to provide oil spill response planners, equipment manufacturers, users, and government agencies with a standard on the equipment selection process for the removal of oil from the marine environment.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.3 This guide does not address the compatability of spill-control equipment with spill products. It is the user's responsibility to ensure that any equipment selected is compatible with anticipated products and conditions.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
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Designation: F 1778 – 97
Standard Guide for
Selection of Skimmers for Oil-Spill Response
This standard is issued under the fixed designation F 1778; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.1.5 throughput effıciency—the ratio, expressed as a per-
centage, of the volume of oil recovered to the volume of oil
1.1 This guide covers considerations for selecting skimmer
encountered.
systems for the recovery of marine-oil spills. The purpose of
(F 631)
this guide is to provide oil spill response planners, equipment
manufacturers, users, and government agencies with a standard
4. Significance and Use
on the equipment selection process for the removal of oil from
4.1 This guide is intended to facilitate the oil spill response
the marine environment.
equipment selection process for local, regional, and national
1.2 This standard does not purport to address all of the
spill response teams. It is not intended to define rigid sets of
safety concerns, if any, associated with its use. It is the
equipment standards.
responsibility of the user of this standard to establish appro-
4.2 The effectiveness of the equipment chosen to combat an
priate safety and health practices and determine the applica-
oil spill will depend on the oil type and environment(s)
bility of regulatory limitations prior to use.
encountered, as well as other factors. This guide is intended to
1.3 This guide does not address the compatibility of spill-
be used by persons generally familiar with the practical aspects
control equipment with spill products. It is the user’s respon-
of oil spill cleanup operations including on-scene response
sibility to ensure that any equipment selected is compatible
coordinators, planners, oil spill management teams, oil spill
with anticipated products and conditions.
removal organizations, and plan evaluators.
2. Referenced Documents 4.3 Eleven general types of skimming systems are described
in this guide. Each description includes a summary of the
2.1 ASTM Standards:
operating principle and a list of selection considerations.
F 625 Practice for Classifying Water Bodies for Spill Con-
4.4 Selection considerations are included to guide the user
trol Systems
on the selection of a particular skimmer type or category. Users
F 631 Guide for Collecting Skimmer Performance Data in
are cautioned that within each category there may be a wide
Controlled Environments
variation in performance among various skimmers.
3. Terminology
4.5 When selecting a skimmer for use in extremely cold
conditions, consideration should be given to the effect of ice
3.1 Definitions:
forming on the skimmer, changes in buoyancy, possible restric-
3.1.1 encounter rate—the volume of oil per unit time
tion of inlets, and changes to hydraulic efficiency. Because
actively directed to the removal mechanism.
there may be wide variations in skimmer performance at
(F 631)
extreme temperatures, even within a given category, ambient
3.1.2 nameplate recovery rate—the maximum skimming
temperature is not included as a selection consideration.
capacity of a device under optimum conditions of oil type,
slick conditions, and environmental conditions.
5. Skimmer Selection Considerations
3.1.3 oil recovery rate—the volume of oil recovered by the
5.1 Selecting a type of skimmer for a given application
device per unit time.
involves examining the skimmer’s likely performance against
(F 631)
a range of operational requirements. The following are recom-
3.1.4 recovery effıciency—the ratio, expressed as a percent-
mended as a guide to this process, with the requirements
age, of the volume of oil recovered to the volume of total fluids
grouped according to the operating environment, the slick
recovered.
conditions, and skimmer performance criteria. Comments on
(F 631)
each of these operational requirements, specific to each skim-
ming type, are given in Section 6.
This guide is under the jurisdiction of ASTM Committee F-20 on Hazardous
5.2 Operating Environment:
Substances and Oil Spill Response and is the direct responsibility of Subcommittee
5.2.1 Wave Conditions—Depending on the type of skimmer,
F20.12 on Removal.
waves may affect both the oil-recovery rate and the oil-
Current edition approved Feb. 10, 1997. Published April 1997.
Annual Book of ASTM Standards, Vol 11.04. recovery efficiency. In general, most skimmers work best in
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1778
calm conditions with decreases in recovery rate and efficiency recovery rates only being achieved with thick slicks. Slick
as waves increase; in particular most skimmers are greatly
thickness also affects the recovery efficiency of most skimmers,
affected by short choppy waves. For each skimming type, in particular those employing suction or weir skimming prin-
comments are given on the sensitivity to different wave
ciples. On the other hand, many skimmers can deal effectively
environments. (Classification information for calm, protected,
with thin slicks by varying the operating parameters of the
and open-water environments is given in Practice F 625.)
device (that is, for oleophilic devices, by reducing the speed of
5.2.1.1 Additional considerations for selecting skimmers for the oleophilic element, and by adjusting the weir settings for
particular wave conditions are that both the skimming device
weir devices).
and the required support platform are applicable to the intended
5.3.2.1 In evaluating a skimming principle based on ex-
environment.
pected slick thickness, consideration should be given to
5.2.2 Currents—Should the operating environment of con-
whether containment booms can be used to concentrate oil for
cern have significant water currents, this should be considered
recovery.
in the selection process. Many skimmers will not operate
5.3.2.2 In the skimmer descriptions in Section 6, reference
effectively in currents greater than 1 knot due to decreases in
is made to device performance in thin slicks, which is defined
throughput efficiency. On the other hand, several skimming
as continuous slicks less than 1 mm in thickness, or discon-
principles such as the sorbent belt, brush, submersion plane,
tinuous patches of oil with an average thickness of less than 1
advancing weir, and boom skimmers rely on relative current
mm.
for effective operation and are applicable in currents greater
5.3.3 Debris—The presence of debris presents two concerns
than 1 knot. Several skimmer types such as the oleophilic brush
in a skimming operation: first; that debris may restrict flow to
and oleophilic rope mop are available as well, in configurations
the skimming head, and second, that debris may interfere
that allow them to operate effectively in high currents.
directly with the skimming component (that is, clogging or
5.2.2.1 Comments on performance in currents are restricted
obstructing openings, impeding moving parts). Some skim-
to those directly related to the skimming device. If containment
ming types, such as most oleophilic devices, are largely
booms are used to collect or concentrate oil, or both, for
insensitive to the presence of debris. Suction and air conveyor
skimming, additional operating limitations related to contain-
devices are generally tolerant of debris up to the size of the
ment boom performance in currents may also apply.
transfer hoses used. Weir devices, in general, are susceptible to
5.2.3 Water Depths—Water depths may be a concern for
clogging with debris; however, many weir devices use integral
skimming operations in nearshore waters and when supporting
transfer pumps that can process a range of debris types. Where
a shoreline cleanup operation. It is important to note that any
applicable, comments are made on debris tolerance or sensi-
draft limitations would apply to both the skimming device as
tivity in the selection considerations comments. It should be
well as the required support vessel; certain skimmer types,
noted that these comments pertain to the general skimming
although not requiring deep water for their skimming compo-
type, and that certain skimmers within a given category may
nent, may require large support vessels for deployment and
include means of dealing with debris. Guidance for a range of
operation.
debris types respecting skimmer performance can be taken
5.2.3.1 While many skimming types are available in a range
from Guide F 631, which lists a number of debris forms for
of sizes that may allow their operation in shallow waters,
skimmer testing.
certain types are generally applicable to shallow water depths
5.4 Performance Requirements:
and these are noted in the skimmer descriptions. Skimmer
types in this category include rope mop skimmers, vacuum
5.4.1 Recovery Rate—For some applications the most im-
systems, air conveyors, some weir skimmers, and some sorbent portant performance criteria will be the product recovery rate.
belt skimmers.
Although the various skimming categories are available in a
5.3 Slick Conditions: range of sizes and capacities, generalizations can be made on
expected recovery rates. In this guide, comments are made on
5.3.1 Oil Type and Viscosity—Few skimming principles
expected recovery rates only as they would apply to the various
operate with optimum effectiveness over a wide range of oil
skimming principles and not to particular devices. For ex-
viscosities. For many skimmers, recovery rates will tend to be
ample, weir skimmers and boom skimmers are available with
less than the reported maximum rates for oils that have a very
high nameplate recovery rates, limited only by the available
low viscosity, and for oils that have a very high viscosity, either
pumping capacity. On the other hand, oleophilic skimmers tend
initially or as a result of weathering or emulsification, or both.
On the other hand, several skimming principles such as brush, to have a fixed upper limit of recovery depending on the size
of the oleophilic surface used (that is, surface area of discs,
drum, and paddle-belt skimmers operate most effectively with
more viscous oils. length and diameter of rope mop).
5.3.1.1 Recommended viscosities for skimmer performance 5.4.1.1 Although specific skimmer performance data are not
data are given in Guide F 631. These include: 200, 2000, and
included in this guide, users are reminded that a skimmer’s
60 000 mm /s. These values are referred to in the skimmer nameplate recovery rate should be used with caution as it may
selection considerations as low, medium, and high viscosity
not accurately reflect skimmer performance under varying
oil.
conditions of slick thickness, slick viscosity, and environmen-
5.3.2 Slick Thickness—Slick thickness greatly affects the tal parameters. Where possible, performance data based on
recovery rate of virtually all skimming principles, nameplate field use or experiments should be used, with reference to the
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1778
slick and environmental conditions of particular concern to the 6.2.2.1 Oil Type—Applicable to low and medium viscosity
user. oils.
6.2.2.2 Debris Tolerance—Debris must be screened or re-
5.4.2 Recovery Effıciency—Selection of a skimmer based on
the expected recovery efficiency may be particularly important moved from the skimmer opening.
depending upon the availability of storage, the availability of 6.2.2.3 Wave Conditions—Recovery rate and efficiency de-
systems to separate free water from the recovered fluids, and graded by choppy waves.
the permissibility of discharging decanted water at the recovery 6.2.2.4 Currents—May be operated at currents greater than
site. The expected recovery efficiency will, for most skimming one knot, at reduced recovery efficiency, by pumping at a high
categories, vary greatly depending on the thickness and vis-
rate.
cosity of the slick and on the environmental conditions at the
6.2.2.5 Water Depth—Generally limited by towing vessels.
spill site.
6.2.2.6 Mode of Application—Requires relative forward
5.4.2.1 In general, skimmers using oleophilic principles can velocity: may be operated in stationary mode if current present.
be expected to have higher recovery efficiencies relative to
6.2.2.7 Other—Typically designed for vessel-of-
skimmers using weir or suction principles. Among weir skim-
opportunity application.
mers, devices in the induced flow category can be expected to
6.3 Brush Skimmers:
have a high efficiency. As well, several skimming categories
6.3.1 Description—Brush skimmers are oleophilic skim-
are typically configured with onboard gravity separation,
mers that pick up oil on the bristles of a brush. There are two
which would enhance their overall efficiency. For skimmers
main configurations for the brushes: drum brush skimmers, in
without onboard separation, oil/water separation should be
which the brushes are mounted around the perimeter of a drum;
considered to maximize the use of available storage.
and chain brush skimmers, in which the brushes are mounted
5.4.3 Mode of Application—Comments on the mode of
on several continuous loop chains. In each case the brushes are
application include the ability to use in an advancing mode and
rotated through the oil/water interface, picking up oil and some
the applicability to use on a vessel-of-opportunity.
water. The recovered fluid is then combed from the bristles into
5.4.3.1 Certain skimmer categories, such as oleophilic disc, a sump. Both brush skimmer types are generally used in an
rope mop, and some weir skimmers are not generally used in
advancing mode. Chain brush skimmers are typically config-
an advancing mode. Conversely, devices such as the boom ured with the skimmer head facing aft, creating a calm area for
skimmer, the fixed submersion plane, paddle belt, and oleo- oil to accumulate and be recovered, reducing the skimmer’s
philic brush skimmers require relative forward motion for sensitivity to waves.
effective operation.
6.3.2 Selection Considerations:
5.4.3.2 Vessel-of-opportunity application will in many cases
6.3.2.1 Oil Type—Applicable to medium and high viscosity
be specific to a skimming device rather than a skimming oils.
category. However f
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