ASTM F1778-97(2002)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F1778–97 (Reapproved 2002)
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 3.1.4 recovery effıciency—the ratio, expressed as a percent-
age, of the volume of oil recovered to the volume of total fluids
1.1 This guide covers considerations for selecting skimmer
recovered.
systems for the recovery of marine-oil spills. The purpose of
(F 631)
this guide is to provide oil spill response planners, equipment
3.1.5 throughput effıciency—the ratio, expressed as a per-
manufacturers, users, and government agencies with a standard
centage, of the volume of oil recovered to the volume of oil
on the equipment selection process for the removal of oil from
encountered.
the marine environment.
(F 631)
1.2 This guide does not address the compatibility of spill-
control equipment with spill products. It is the user’s respon-
4. Significance and Use
sibility to ensure that any equipment selected is compatible
4.1 This guide is intended to facilitate the oil spill response
with anticipated products and conditions.
equipment selection process for local, regional, and national
1.3 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
2. Referenced Documents be used by persons generally familiar with the practical aspects
of oil spill cleanup operations including on-scene response
2.1 ASTM Standards:
coordinators, planners, oil spill management teams, oil spill
F 625 Practice for Classifying Water Bodies for Spill Con-
removal organizations, and plan evaluators.
trol Systems
4.3 Elevengeneraltypesofskimmingsystemsaredescribed
F 631 Guide for Collecting Skimmer Performance Data in
in this guide. Each description includes a summary of the
Controlled Environments
operating principle and a list of selection considerations.
3. Terminology
4.4 Selection considerations are included to guide the user
ontheselectionofaparticularskimmertypeorcategory.Users
3.1 Definitions:
are cautioned that within each category there may be a wide
3.1.1 encounter rate—the volume of oil per unit time
variation in performance among various skimmers.
actively directed to the removal mechanism.
4.5 When selecting a skimmer for use in extremely cold
(F 631)
conditions, consideration should be given to the effect of ice
3.1.2 nameplate recovery rate—the maximum skimming
formingontheskimmer,changesinbuoyancy,possiblerestric-
capacity of a device under optimum conditions of oil type,
tion of inlets, and changes to hydraulic efficiency. Because
slick conditions, and environmental conditions.
there may be wide variations in skimmer performance at
3.1.3 oil recovery rate—the volume of oil recovered by the
extreme temperatures, even within a given category, ambient
device per unit time.
temperature is not included as a selection consideration.
(F 631)
5. Skimmer Selection Considerations
This guide is under the jurisdiction of ASTM Committee F20 on Hazardous
5.1 Selecting a type of skimmer for a given application
Substances and Oil Spill Response and is the direct responsibility of Subcommittee
involves examining the skimmer’s likely performance against
F20.12 on Removal.
a range of operational requirements. The following are recom-
Current edition approved Oct. 10, 2002. Published February 2003. Originally
approved in 1997. Last previous edition approved in 1997 as F 1778 – 97.
mended as a guide to this process, with the requirements
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
grouped according to the operating environment, the slick
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
conditions, and skimmer performance criteria. Comments on
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1778–97 (2002)
each of these operational requirements, specific to each skim- 5.3.1.1 Recommended viscosities for skimmer performance
ming type, are given in Section 6. data are given in Guide F 631. These include: 200, 2000, and
60 000 mm /s. These values are referred to in the skimmer
5.2 Operating Environment:
selection considerations as low, medium, and high viscosity
5.2.1 Wave Conditions—Dependingonthetypeofskimmer,
oil.
waves may affect both the oil-recovery rate and the oil-
5.3.2 Slick Thickness—Slick thickness greatly affects the
recovery efficiency. In general, most skimmers work best in
recovery rate of virtually all skimming principles, nameplate
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
thicknessalsoaffectstherecoveryefficiencyofmostskimmers,
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 Additionalconsiderationsforselectingskimmersfor
the oleophilic element, and by adjusting the weir settings for
particular wave conditions are that both the skimming device
weir devices).
andtherequiredsupportplatformareapplicabletotheintended
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
effectively in currents greater than 1 knot due to decreases in 5.3.2.2 In the skimmer descriptions in Section 6, reference
throughput efficiency. On the other hand, several skimming is made to device performance in thin slicks, which is defined
principles such as the sorbent belt, brush, submersion plane, as continuous slicks less than 1 mm in thickness, or discon-
advancing weir, and boom skimmers rely on relative current tinuous patches of oil with an average thickness of less than 1
for effective operation and are applicable in currents greater
mm.
than1knot.Severalskimmertypessuchastheoleophilicbrush
5.3.3 Debris—Thepresenceofdebrispresentstwoconcerns
andoleophilicropemopareavailableaswell,inconfigurations
in a skimming operation: first; that debris may restrict flow to
that allow them to operate effectively in high currents.
the skimming head, and second, that debris may interfere
5.2.2.1 Comments on performance in currents are restricted directly with the skimming component (that is, clogging or
tothosedirectlyrelatedtotheskimmingdevice.Ifcontainment
obstructing openings, impeding moving parts). Some skim-
booms are used to collect or concentrate oil, or both, for
ming types, such as most oleophilic devices, are largely
skimming, additional operating limitations related to contain-
insensitive to the presence of debris. Suction and air conveyor
ment boom performance in currents may also apply.
devices are generally tolerant of debris up to the size of the
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
draft limitations would apply to both the skimming device as applicable, comments are made on debris tolerance or sensi-
well as the required support vessel; certain skimmer types, tivity in the selection considerations comments. It should be
although not requiring deep water for their skimming compo- noted that these comments pertain to the general skimming
nent, may require large support vessels for deployment and type, and that certain skimmers within a given category may
operation. include means of dealing with debris. Guidance for a range of
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
and these are noted in the skimmer descriptions. Skimmer
5.4 Performance Requirements:
types in this category include rope mop skimmers, vacuum
5.4.1 Recovery Rate—For some applications the most im-
systems,airconveyors,someweirskimmers,andsomesorbent
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
expectedrecoveryratesonlyastheywouldapplytothevarious
operate with optimum effectiveness over a wide range of oil
viscosities. For many skimmers, recovery rates will tend to be skimming principles and not to particular devices. For ex-
ample, weir skimmers and boom skimmers are available with
less than the reported maximum rates for oils that have a very
lowviscosity,andforoilsthathaveaveryhighviscosity,either high nameplate recovery rates, limited only by the available
pumpingcapacity.Ontheotherhand,oleophilicskimmerstend
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).
F1778–97 (2002)
5.4.1.1 Although specific skimmer performance data are not width. Although such a system would be similar to a boom
included in this guide, users are reminded that a skimmer’s skimmer, it would not meet the definition of a boom skimmer
nameplate recovery rate should be used with caution as it may because the skimmer in the system could be used apart from
not accurately reflect skimmer performance under varying the boom. In a boom skimmer, the skimmer is part of the boom
conditions of slick thickness, slick viscosity, and environmen- and is not intended to be used by itself.
tal parameters. Where possible, performance data based on
6.2.2 Selection Considerations:
field use or experiments should be used, with reference to the
6.2.2.1 Oil Type—Applicable to low and medium viscosity
slick and environmental conditions of particular concern to the
oils.
user.
6.2.2.2 Debris Tolerance—Debris must be screened or re-
5.4.2 Recovery Effıciency—Selectionofaskimmerbasedon
moved from the skimmer opening.
the expected recovery efficiency may be particularly important
6.2.2.3 Wave Conditions—Recovery rate and efficiency de-
depending upon the availability of storage, the availability of
graded by choppy waves.
systems to separate free water from the recovered fluids, and
6.2.2.4 Currents—May be operated at currents greater than
thepermissibilityofdischargingdecantedwaterattherecovery
one knot, at reduced recovery efficiency, by pumping at a high
site. The expected recovery efficiency will, for most skimming
rate.
categories, vary greatly depending on the thickness and vis-
6.2.2.5 Water Depth—Generally limited by towing vessels.
cosity of the slick and on the environmental conditions at the
6.2.2.6 Mode of Application—Requires relative forward
spill site.
velocity:maybeoperatedinstationarymodeifcurrentpresent.
5.4.2.1 In general, skimmers using oleophilic principles can
6.2.2.7 Other—Typically designed for vessel-of-
be expected to have higher recovery efficiencies relative to
opportunity application.
skimmers using weir or suction principles. Among weir skim-
6.3 Brush Skimmers:
mers, devices in the induced flow category can be expected to
6.3.1 Description—Brush skimmers are oleophilic skim-
have a high efficiency. As well, several skimming categories
mers that pick up oil on the bristles of a brush. There are two
are typically configured with onboard gravity separation,
main configurations for the brushes: drum brush skimmers, in
which would enhance their overall efficiency. For skimmers
whichthebrushesaremountedaroundtheperimeterofadrum;
without onboard separation, oil/water separation should be
and chain brush skimmers, in which the brushes are mounted
considered to maximize the use of available storage.
on several continuous loop chains. In each case the brushes are
5.4.3 Mode of Application—Comments on the mode of
rotated through the oil/water interface, picking up oil and some
application include the ability to use in an advancing mode and
water.Therecoveredfluidisthencombedfromthebristlesinto
the applicability to use on a vessel-of-opportunity.
a sump. Both brush skimmer types are generally used in an
5.4.3.1 Certain skimmer categories, such as oleophilic disc,
advancing mode. Chain brush skimmers are typically config-
rope mop, and some weir skimmers are not generally used in
ured with the skimmer head facing aft, creating a calm area for
an advancing mode. Conversely, devices such as the boom
oil to accumulate and be recovered, reducing the skimmer’s
skimmer, the fixed submersion plane, paddle belt, and oleo-
sensitivity to waves.
philic brush skimmers require relative forward motion for
6.3.2 Selection Considerations:
effective operation.
5.4.3.2 Vessel-of-opportunityapplicationwillinmanycases
6.3.2.1 Oil Type—Appli
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