Flow Sites indicate flow via a glass window and can be offered with a flapper, rotator, drip tube or gaseous.
|DWF||Plain Dual-Window NPT SFI|
|DWFF||Dual-Window NPT SFI (Flapper)|
|DWFR||Dual-Window NPT SFI (Rotator)|
|DWFD||Dual-Window NPT SFI (Drip Tube)|
|DWFG||Dual-Window NPT SFI (Gaseous)|
External mechanical impact - if the outer glass is cracked or shattered, the inner glass can temporarily continue in service until the unit can be repaired or replaced.
Abnormal compressive forces - in maintenance or replacement situations, the housing assists in alignment of the glass and can absorb uneven or excessive compression.
Thermal shock - in high temperature applications the inner and outer glass protect one another from an extreme thermal gradient. The air pocket between the glass provides an insulative effect.
Corrosion/erosion - if the inner glass is weakened and it breaks, the outer glass can temporarily contain the fluid, withstand the pressure, and continue in service until the unit can be repaired or replaced.