The style P sight glass has a plain spout cast in the body and is used to check for the presence of a liquid where there is intermittent flow, partially filled lines or entrained air.

It can be used vertical or horizontal lines. The integral drip lip makes it ideal for leak detection.

Sight glasses and sight flow indicators are primarily used to view the flow of gas or liquids within the water, chemical, oil and gas, power, pharmaceutical and food processing industries.

Sight flow indicators are used to view the flow of gas and liquids giving a clear visual indication of flow within a pipeline or vessel and leak detection for plant and equipment protection.


Body – Primary Flowpoints can supply sight glasses in special materials such as super duplex or low carbon steels. Sight glasses conforming to NACE MR0175 can be produced. For particularly corrosive applications the body and flap can be lined with HALAR, ECTFE or PFA.

Glass – High pressure toughened soda lime to BS3463 rated to 60 bar, toughened borosilicate to BS3463 or DIN7080 rated up to 16 bar. The high pressure range uses powder coated mild steel covers as standard. Stainless steel covers are available as an option.

Output – A flow switch can be fitted to the indicator to give an alarm if the flow moves above or below a preset value.

Order Details for Style ‘P’

Code Description
SP       Stainless steel body BS 1504 316 C16
CP       Carbon steel body BS 1504 162 GR480
        Glass Material & Pressure Range
        Toughened soda lime glass to BS3463 rated to 16 bar (standard)
  H     Toughened soda lime glass to BS3463 rated to 40 bar
  B     Toughened borosilicate glass to BS3463
  HB     Toughened borosilicate glass to DIN 7080
      Indicator Size
  015   15mm / ½”
  020   20mm / ¾”
  025   25mm / 1”
  040   40mm / 1 ½”
  050   50mm / 2”
  080   80mm / 3”
  100   100mm / 4”
  150   150mm / 6”
  200   200mm / 8”
    End Connection
  A ANSI 150
  C ANSI 300
  N PN16
  1 BSP
  2 BSPT
  3 NPT
  4 Socket Weld