Krom Schroder DG50T 84447820 Gas Pressure Switch

Krom Schroder DG50T 84447820 Pressure Switch (DG 50T-21N)

The Krom Schroder DG50T 84447820 (Model: DG 50T-21N) is a diaphragm-actuated, adjustable gas and air pressure switch designed for continuous safety interlock, threshold detection, and automatic-reset switching in combustion systems. Calibrated for a switching threshold range between 2.5 and 50 mbar (1 to 20 “WC), the DG50T monitors positive, negative, or differential pressure across natural gas lines, LPG feeds, flue gas channels, and forced-draft combustion air supplies.

The unit features an integrated vent limiter orifice complying with North American and international safety codes, a 1/2″ NPT conduit connection for secure electrical integration, and an integrated 120 V AC blue indicator lamp for clear visual status determination.

Model Details:

• Manufacturer: Kromschröder / Honeywell Thermal Solutions (HTS)
• Full Model Code: DG 50T-21N
• Manufacturer Part Number (MPN): 84447820
• Alternative/Ordering Part Number: KS84447820
• Equivalent / Alternative Replacements:
  • Honeywell C6097A1053/U
  • Honeywell C6097B1119/U
  • Honeywell C6097B3119/U
  • Honeywell C6097A3053/U
  • Kromschröder DG 50T-22N (Dual 1/4″ NPT variant, MPN: 84447822)

Key Features

• Adjustable Setpoint Range (2.5 to 50 mbar / 1 to 20 “WC): Continuous handwheel adjustment with an indexed, tamper-evident dial enables precise threshold trip configuration under varying fuel train pressures.
• Automatic Reset Operation: Re-engages contacts seamlessly when line pressure normalizes within the narrow switching differential window (≤ 1.5 mbar hysteresis).
• Built-in Vent Limiter: Pre-fitted internal flow limiter eliminates the mandatory vent-to-atmosphere piping requirement under NFPA 86 and standard mechanical installation codes.
• 120 V AC Blue Pilot Lamp: Built-in optical state indication provides immediate fault tracing and operational feedback across low-light burner platforms.

Technical Specifications

Compatible Equipment Models

• Kromschröder Burner Controls: BCU 370, BCU 460, BCU 480, IFD 258, IFS 110IM, and PFS 778 series.
• Honeywell Flame Safeguard Controls: RM7800 series, 7800 Series Relay Modules (EC7800, RM7840, RM7895).
• Valve Trains & Manifolds: Kromschröder modular gas trains (VGBF, VCG, VAG, VAS, and VK series safety shut-off valves).
• Industrial Burners: Package burners from Maxon, Eclipse, Riello, Weishaupt, and direct-fired industrial furnace burners (e.g., BIC, BIO series).

Applications

• Minimum Gas Pressure Interlock (Low-Gas Cutoff): Secures the gas supply train to ensure that supply headers deliver fuel above burner stall and flameout thresholds.
• Combustion Air Proving: Interlocks differential pressure across forced draft blowers to verify sustained air volume before enabling pilot ignition.
• Filter Differential Pressure Monitoring: Detects excess particulate and debris clogging across pipeline gas strainers and air intake plenum stages.
• Flue Gas & Exhaust Overpressure Cutout: Prevents hazardous blow-back inside thermal oxidizers, waste incinerators, and inert gas generators by halting firing if back-pressure spikes.
• Marine Auxiliary Boilers & Inert Gas Systems (IGS): Monitors deck seal gas pressure and fuel valve train manifolds on commercial vessels and offshore platforms.

Frequently Asked Questions

What is the switching differential of the Krom Schroder DG50T?

The switching differential (hysteresis) of the DG50T is at or below 1.5 mbar (0.6 “WC). It trips at the set point on rising pressure and resets automatically as pressure drops below the hysteresis deadband.

Does the DG50T-21N require a manual reset after tripping?

No. The “T” designator combined with standard designation identifies this as an automatic reset unit. For manual lockout versions that hold their state until locally reset by an operator, you must specify the DG 50HT (lockout on rising pressure) or DG 50NT (lockout on falling pressure).

Can the DG50T be used on aggressive gases like pure oxygen or ammonia?

Standard DG50T units with NBR diaphragms are approved only for fuel gases (natural gas, propane, butane, town gas) and non-corrosive air/exhaust streams. Ammonia and pure oxygen require the specialized DG..S series fitted with custom diaphragm elastomers and degreased chambers.

What is the purpose of the blue pilot light on this model?

The integrated 120 V AC blue pilot lamp (signified by code ‘N’) is wired to provide instantaneous visual indication when the switch contacts are energized, allowing boiler technicians to identify fuel train line faults from across the floor plate.

Can I install this switch outdoors or on an open weather deck?

Yes, provided the 1/2″ NPT electrical conduit entry is properly sealed with an approved cable gland or conduit fitting and the clear dial cover is screwed down tightly against its perimeter gasket to preserve the IP65 / NEMA 4 rating.