FM Approved


PTFE and Glass Wetted Surfaces

The FLO-VU 360L sight glass: 1" through 12" diameter, featuring a full 360° unobstructed view with the high temperature and near-universal corrosion resistance of PTFE.

FLO-VU® Unique Seal Design

A unique PTFE / Viton® envelope-type gasket provides a secure, bubble-tight seal even in applications with extreme thermal cycling.

Pressure Rating

1/2" to 6" full vacuum to 150 psi
8" - 10" full vacuum to 85 psi
12" full vacuum to 65 psi
-20°F to 400°F.

Lexan® Impact Shield

A Lexan® outer safety shield (with an unobstructed 360° view) is provided on the FLO-VU 360L.

Standard overall lengths of 8" are stocked at the factory, with quick delivery available for special lengths. 316 Stainless Steel flanges (PTFE / PFA lined) and 304 Stainless Steel hardware provide external corrosion resistance.

Additional Features:

  • Passes steam-cold water cycling tests (ASTM F-423)
  • 100% testing and certification
  • Polycarbonate or Slotted Metal Shields
  • Availability of unlined 316 Stainless Steel Flanges with the FLO-VU 360M.

FLO-VU® Options Available:

Gas Purge Ring - for purging and environmental control of the annular area between the glass tube and shield.

General Purpose and Explosion Proof Light - for back-lighting through windows in difficult lighting installations.

Vertical Drip Tube - for easy viewing of low flow rates in vertical installations.

Horizontal Flapper - for visual indication of low rates in horizontal installations.

Viton® is a registered trademark of DuPont Dow Elastomers

Download FLO-VU Brochure


  • Pressure Rating Up to 150 @ 400°F
  • Temperature Range -20° to 400°F
  • Vacuum Rating Full Vacuum
  • Flange Material 316 Stainless Steel
  • Glass Tube Borosilicate
  • Impact Shield Lexan®
  • Flange Liner PTFE / PFA


Nominal Diameter Lengths Available Lengths Stocked
Lengths 5" through 50" … 8" OAL Stocked at Factory
1" 5"-50" 8"
1 1/2" 5"-50" 8"
2" 5"-50" 8"
3" 5"-50" 8"
4" 5"-50" 8"
6" 5"-50" 8"
8" 5"-50" 8"
10" 5"-50" 8"
12" 5"-50" 8"

Double-Sure™ Dual Containment Glass Sight Flow Indicators

Double Sure

Double-Sure Dual Containment Glass Sight Flow Indicators are specifically designed to provide an extra level of safety, reliability, and protection in high pressure and high temperature conditions typically found in ultrapure processing environments.

  • Dual Containment
    Each unit is double sealed for extra safety and reliability.
  • Pressure
    rating 150 psig
  • Operating Temperature
    -20°F to 350°F (-29°C to 176°C)
  • 100% Tested
    The inner chamber is subjected to both a 225 psig hydrostatic pressure test and a 150 psig helium bubble test, while the outer chamber is subjected to a 150 psig helium bubble test.
  • Lexan® Impact Shield
    A Lexan® outer safety shield with an unobstructed 360° view is standard on all Double-Sure Dual containment Sight Flow Indicators to protect the glass tube from external damage and to provide scatter protection.
  • PTFE and Glass-Wetted Surface
    PTFE and borosilicate glass-wetted surfaces offer high temperature corrosion resistance and absolute product purity.
  • Unique Seal Design
    PTFE and Viton® B gasket provides a secure, bubble-tight seal in applications with extreme thermal cycling.
  • Rugged Construction
    All Double-Sure Dual Containment Sight Flow Indicators have heavy-duty tie rods and flanges for decreased deformation under external loads.
  • Variety of Sizes
    Available in diameters of 1", 1-1/2" and 2" in lengths up to 50".

Pure-Vu Sanitary Sight Flow Indicator

Pure-Vu Sight Flow Indicator

The Pure-Vu Sight Flow Indicator is made for pharmaceutical, food, and other sterile process industries requiring sanitary cleanliness. Designed to mount in-line for high purity pipe systems with tri-clamp connections in sizes 1" - 4" diameter.

Providing a sterile, clear borosilicate glass tube 360° view, the sight area is easily seen, with a greater view than bull's eye type sight glass.

An all-stainless steel polished construction is close tolerance sealed to prevent contamination using FDA compliant materials. A polycarbonate cover shield over the glass prevents mechanical damage and in the event of pressure upset, will prevent a spray out. The unit is rated for 150 psi pressure/Full vacuum from -20°F to 350°F. Each unit is hydrotested and helium bubble checked prior to shipment.

The unit has 4 tie rods that tighten only to the proper torque necessary to seal the unit. Components can be replaced in the field. The sightglass can be CIP, sterilized, or autoclaved.

Pure-Vu™ sight flow indicators offer the ultimate design for safety in process. A unique seal design offers optimal performance in a sanitary process environment.

Download Pure-Vu Brochure


  • Sizes 1" - 4" diameter
  • Borosilicate Glass Tube
  • 360° View
  • Stainless Steel Polished Construction
  • FDA Compliant Materials
  • Rated for 150 psi
  • Full Vacuum from -20°F to 350°F

FLO-VU® Sight-Float Check Valve

FLO-VU Sight-Float Check Valve

The FLO-VU Sight-Float Check Valve is intended for use in vertical sampling applications and as a means of preventing vacuum scrubber contamination due to over-filling of the vertical sample leg or vessel before draining back into the sample container.

Standard construction includes type 316 stainless steel flanging, 304 hardware and PTFE / glass lined wetted surfaces. Polycarbonate shield tubes are provided on all units. The hollow ball float is molded from PTFE and seals into a soft seat made of a white Chemraz® fluoroelastomer.

Units have a full vacuum to 150 psi rating at temperatures from -20° up to 300°F.

Options Available:

Gas Purge Ring - for purging and environmental control of the annular area between the glass tube and shield.

General Purpose and Explosion Proof Light - for back-lighting through windows in difficult lighting installations.


  • Type 316 stainless steel flanging
  • 304 hardware and PTFE/glass lined wetted surfaces
  • Polycarbonate shield tubes
  • PTFE hollow ball float
  • Chemraz® Fluoroelastomer Soft Seat
  • Full vacuum to 150 psi
  • Temperatures from -20° up to 300°F

Bull's Eye Sight Indicators

Bull's Eye

Guaranteed Not to Leak

Flo-Vu® PFA lined Bull’s Eye sight indicators are ideal for visual fluid motion, flow & color inspection. They are designed for tough applications that require a rugged ductile iron housing and thick Borosilicate glass for impact resistance. Flo-Vu’s PFA lining provides the ultimate in chemical resistance from (-)20°F to (+)400°F and is full vacuum rated.

Flo-Vu is resistant to:

  • All acids
  • All solvents
  • All organic and inorganic chlorides & sulfates
  • All bleach solutions
  • All phenols
  • All caustics
  • All peroxides

When compared to competitive brands, Flo-Vu excels with 1-1/2 times more viewing area, powder coat epoxy paint standard and an integral drip lip at no extra charge.


Larger sizes available
Size Length Flare Diameter
1" 6" 2"
1-1/2" 7" 2-1/2"
2" 8" 3-1/8"
3" 9-1/2" 5-1/8"
4" 11-1/2" 6-5/16"
6" 14" 8"
Bull's Eye Dimensions

Parts & Material

Designation ASTM / Material
Body Ductile Iron ASTM A395
Lining PFA
Glass Borosilicate - Option w/ Clear FEP
Gasket Asbestos Free - Compressed Sheet
Stud Fastener Zinc Plated ASTM A193 Gr. B7
Hexagon Nut Zinc Plated ASTM A194 Gr. 2H
Bull's Eye Parts


Download Bull's Eye Brochure

How to Order

Size Part Number
*Substitute “A” for the following options B = FEP sheet under glass C = Special Bolting hardware
1" SFB - DI - 100 - *A
1-1/2" SFB - DI - 150 - *A
2" SFB - DI - 200 - *A
3" SFB - DI - 300 - *A
4" SFB - DI - 400 - *A
6" SFB - DI - 600 - *A