DIG - Rotating Vane Flow Indicator

Visual Flow Indication Solution for Liquid Applications

The KOBOLD DIG rotating vane flow indicator provides reliable visual confirmation of liquid flow in piping systems where flow indication is required without measurement capabilities. Designed for applications demanding simple, dependable flow presence verification, this paddlewheel flow indicator uses a high-visibility orange polypropylene vane wheel that rotates when fluid passes through the housing, offering immediate visual feedback on flow status.

Engineered for industrial environments, the DIG sight flow indicator is available with three housing material options—brass, stainless steel, or polypropylene—enabling compatibility across corrosive and non-corrosive fluid applications. The rotating vane mechanism operates on a ceramic axle with polysulfone cover, providing durable performance in demanding process conditions.

Key Features and Technical Specifications

The DIG flow indicator accommodates flow ranges from 0.13-3.2 GPM up to 0.79-21 GPM for water-based liquids, with connection sizes ranging from 1/8 inch to 1 inch NPT threads. Maximum operating pressure reaches 230 PSI (16 bar) for brass and stainless-steel models, with polypropylene housings rated to 100 PSI (7 bar). Temperature capabilities extend to 176°F (80°C) across all material combinations.

The unit's pressure drop at maximum flow is only 14.5 PSI, helping reduce energy consumption in pumping systems. Installation flexibility is enhanced by the device's ability to be mounted in any position, though flow must always be in the direction indicated by the arrow marking. No straight pipe runs are required before or after the indicator, simplifying integration into existing piping systems.

Build America, Buy America Act (BABA) Compliance

The KOBOLD DIG rotating vane flow indicator is made in the USA and fully compliant with Build America, Buy America Act (BABA) requirements. Manufactured at KOBOLD's Pittsburgh, Pennsylvania facility, this domestically produced flow indicator meets federal mandates for infrastructure projects, water treatment facilities, and public works applications funded by federal dollars.

Specifying BABA compliant instrumentation ensures project eligibility for federal funding programs while supporting American manufacturing. Government agencies, municipalities, and contractors working on federally funded projects can confidently specify the DIG flow indicator to meet domestic content requirements. This compliance provides advantages for water infrastructure projects, wastewater treatment systems, municipal facilities, and other public sector applications.

Application Versatility Across Industries

The DIG visual flow indicator serves diverse industries requiring simple flow verification. Water treatment and distribution systems use these indicators to monitor flow presence at critical points without the complexity of electronic flow measurement. HVAC systems, cooling water circuits, industrial machinery, and equipment manufacturing operations frequently specify rotating vane flow indicators for visual flow confirmation during operation and maintenance procedures. The clear sight window allows operators to quickly verify flow presence and identify flow interruptions without instrumentation.

Material Combination Options

The DIG series offers three material configurations to match application requirements. The DIG-11 series features brass housing with NBR seals, suitable for general water and compatible liquid applications. The DIG-14 series provides stainless steel housing with FKM seals, for a wide variety of media compatibility. The DIG-18 series utilizes polypropylene housing with NBR seals for mildly corrosive chemicals and other compatible media.

All configurations include polypropylene vane wheels and ceramic axles for consistent performance across operating conditions. The polysulfone cover provides chemical resistance and clarity for visual observation.

Installation Advantages

Installation is straightforward using standard NPT threaded connections, with thread sealant recommended for leak-free operation. The compact dimensions and multiple connection sizes enable retrofitting into existing piping systems without major modifications.

Comparison to Alternative Flow Indication Technologies

When compared to ball-type sight flow indicators, flap indicators, or passive sight glasses, the rotating paddlewheel mechanism provides clearer indication of flow movement and direction. The continuously rotating vane wheel is particularly useful with clear or colorless fluids where flow may be difficult to observe through static sight windows without moving elements. The rotating motion remains visible even at lower flow rates within the device's specified range.

Compared to flow indicators with internal flap elements, the paddle wheel design offers less flow restriction and more consistent visual indication across varying flow rates. Unlike sight glasses that only allow viewing of fluid presence without confirming movement, the DIG's rotating mechanism positively indicates active flow versus static fluid in the line.

To learn more about flow indicators, please visit our in depth article about Flow Indicators.

Understanding Flow Indicators Versus Flow Meters

Flow indicators like the DIG are designed to provide visual confirmation of flow presence and relative flow activity, not to measure or quantify flow rates. This distinction makes flow indicators ideal for applications where operators need to verify that flow is occurring without requiring precise flow rate data. For applications requiring flow rate measurement, totalizing, or process control outputs, electronic paddle wheel sensors or other flow measurement technologies would be specified instead.

The DIG rotating vane flow indicator fills the need for simple, reliable, maintenance-free flow indication in systems where visual confirmation is sufficient and electronic measurement is unnecessary or cost-prohibitive.