"dip tube" meaning in English

{
  "forms": [
    {
      "form": "dip tubes",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "dip tube (plural dip tubes)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "ref": "1999, R. Dodge Woodson, Plumber's Standard Handbook, pages 25–19",
          "text": "If the pilot light lights but continues to go out, replace the thermocoupling. If none of these methods prove fruitful, check the dip tube.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A tube in a boiler that directs incoming cold water to the bottom of the tank, to be heated."
      ],
      "id": "en-dip_tube-en-noun-3BjxiKCP",
      "links": [
        [
          "boiler",
          "boiler"
        ],
        [
          "tank",
          "tank"
        ],
        [
          "heat",
          "heat"
        ]
      ]
    }
  ],
  "word": "dip tube"
}

{
  "forms": [
    {
      "form": "dip tubes",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "dip tube (plural dip tubes)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "English terms with quotations",
        "Quotation templates to be cleaned"
      ],
      "examples": [
        {
          "ref": "1999, R. Dodge Woodson, Plumber's Standard Handbook, pages 25–19",
          "text": "If the pilot light lights but continues to go out, replace the thermocoupling. If none of these methods prove fruitful, check the dip tube.",
          "type": "quotation"
        }
      ],
      "glosses": [
        "A tube in a boiler that directs incoming cold water to the bottom of the tank, to be heated."
      ],
      "links": [
        [
          "boiler",
          "boiler"
        ],
        [
          "tank",
          "tank"
        ],
        [
          "heat",
          "heat"
        ]
      ]
    }
  ],
  "word": "dip tube"
}