ASTM D7978-14
采用不流动的触变胶体培养法测定燃料和有关的水中能独立生存的好氧微生物含量的标准试验方法

Standard Test Method for Determination of the Viable Aerobic Microbial Content of Fuels and Associated Water—Thixotropic Gel Culture Method

被代替

ASTM D7978-14 发布历史

ASTM D7978-14由美国材料与试验协会 US-ASTM 发布于 2014。

ASTM D7978-14 发布之时，引用了标准

• ASTM D1129 与水相关的标准术语
• ASTM D1655 航空涡轮燃料标准规范
• ASTM D4175 石油产品、液体燃料和润滑剂相关标准术语
• ASTM D4176 馏分燃料中游离水和颗粒杂质的标准测试方法(外观检查法)
• ASTM D6469 燃料和燃料系统中微生物污染的标准指南
• ASTM D6974 液体燃料中活菌和真菌计数的标准实施规程&x2014；过滤和培养程序
• ASTM D7464 微生物试验用液体燃料、相关材料和燃料系统部件的手动取样的标准实施规程
• ASTM D7847 微生物试验方法的实验室间研究的标准指南
• ASTM D975 柴油标准规范
• ASTM E2756 关于抗菌和抗病毒药物的标准术语
• ISO 8217 石油产品.燃料(F级).船用燃料规格

ASTM D7978-14的历代版本如下：

• 2019年 ASTM D7978-14(2019) 测定燃料和相关水的活性需氧微生物含量的标准试验方法&x2014；触变凝胶培养法
• 2014年 ASTM D7978-14 采用不流动的触变胶体培养法测定燃料和有关的水中能独立生存的好氧微生物含量的标准试验方法

5.1 This test method is intended to provide a tool for assessing whether fuel storage and distribution facilities or end user fuel tanks are subject to microbial growth and alert fuel suppliers or users to the potential for fuel quality or operational problems and/or the requirement for preventative or remedial measures.

5.2 This test method detects numbers of microbial colony forming units (CFU), the same detection parameter used in the laboratory standard procedures Practice D6974 and IP 385. However, whereas Practice D6974 and IP 385 provide separate assessment of numbers of viable aerobic bacteria CFU and numbers of viable fungal CFU, this test method provides a combined total count of viable aerobic bacteria and fungal CFU.

5.3 This test method is designed to detect a recognized group of microorganisms of significance in relation to contamination of distillate fuels, but it is recognized that microbiological culture techniques do not detect all microorganisms that can be present in a sample. Culturability is affected primarily by the ability of captured microbes to proliferate on the growth medium provided, under specific growth conditions. Consequently, a proportion of the active or inactive microbial population present in a sample can be viable but not detected by any one culture test.7 In this respect, the test is indicative of the extent of microbial contamination in a sample ,and it is assumed that when a fuel sample is significantly contaminated, some of the dominant microbial species present will be quantifiably detected, even if not all species present are culturable.

5.4 Many samples from fuel systems can be expected to contain a low level of “background” microbial contamination, which is not necessarily of operational significance. The minimum detection level of this test method is determined by the volume of specimen tested and is set such that microbial contamination will generally only be detected when it is at levels indicative of active proliferation.

5.5 The test will detect culturable bacteria and fungi that are metabolically active and dormant fungal spores. Presence of fungal spores in a fuel sample can be indicative of active microbial proliferation within a fuel tank or system, but at a point distant from the location sampled. Active microbial growth only occurs in free water, and this can be present only as isolated pockets at tank or system low points. Because fungal spores are more hydrophobic than active cells and fungal material (mycelium), they disperse more readily in fuel phase and are thus more readily detected when low points cannot be directly sampled and only fuel phase is present in samples.

5.6 This test method can determine whether microbial contamination in samples drawn from fuel tanks and systems is absent or present at light, moderate, and heavy levels.

5.7 The categorization of light, moderate, and heavy levels of contamination will depend on the fuel type, the sampling location, the facility sampled, and its specific operating circumstances.

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标准号

ASTM D7978-14

发布

2014年

发布单位

美国材料与试验协会

替代标准

ASTM D7978-14(2019)

当前最新

ASTM D7978-14(2019)

 

 

引用标准

ASTM D1129 ASTM D1655 ASTM D4175 ASTM D4176 ASTM D6469 ASTM D6974 ASTM D7464 ASTM D7847 ASTM D975 ASTM E2756 ISO 8217

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