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MCDONNELLReplacement HVACR Pumps, Valves & Tubing

MCDONNELL 51-2-HD Head Mechanism

The MCDONNELL & MILLER 51-2-HD is a replacement head mechanism for HVACR pumps, valves, and tubing. This component is compatible with manufacturer part number 51-2 and carries the manufacturer part number 51-2-HD.

SKU 3G-OTH-76605

Also listed as: 512HD · 51 2 HD

Brand
MCDONNELL
Item
51-2-HD Head Mechanism
Part Number
51-2-HD
Category
Replacement HVACR Pumps, Valves & Tubing
Available to Order
Also known as:51-2-HDMCDONNELL
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Technical Specifications

MCDONNELL
Manufacturer Part Number
51-2-HD
Product Type
Head Mechanism
Compatible Manufacturer Part Number
51-2

Technical Documents

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MCDONNELL Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The MCDONNELL & MILLER 51-2-HD is a replacement head mechanism for HVACR pumps, valves, and tubing. This component is compatible with manufacturer part number 51-2 and carries the manufacturer part number 51-2-HD.

Frequently Asked Questions

What is the MCDONNELL & MILLER 51-2-HD head mechanism used for?

The MCDONNELL & MILLER 51-2-HD is a replacement head mechanism used in HVACR pumps, valves, and tubing systems. It is designed to replace the 51-2 model, restoring proper flow control and safety shutoff functions in commercial heating and cooling applications.

What are the specifications of the MCDONNELL & MILLER 51-2-HD?

The MCDONNELL & MILLER 51-2-HD is a head mechanism with manufacturer part number 51-2-HD. It is compatible with manufacturer part number 51-2. This component is classified as a replacement part for HVACR pumps, valves, and tubing systems.

Where to buy the MCDONNELL & MILLER 51-2-HD worldwide?

3G Electric supplies the MCDONNELL & MILLER 51-2-HD head mechanism worldwide. As a global industrial equipment distributor, we handle full logistics, customs clearance, and delivery to your location. Contact us for availability and lead time.

How to install the MCDONNELL & MILLER 51-2-HD head mechanism?

To install the MCDONNELL & MILLER 51-2-HD, first isolate power and drain the system. Remove the old head mechanism and gasket, then fit the new 51-2-HD unit, ensuring proper alignment with the valve stem. Reassemble, pressurize, and test for leaks per manufacturer guidelines.

Used in

Common applications for MCDONNELL
Steam boiler low-water cutoff — McDonnell & Miller 61 level control
Condensate receiver level monitoring — McDonnell & Miller RS-4-BR-1 4-level sensor
HVACR pump suction filtration — McDonnell & Miller 340700 strainer basket assembly
Flow switch head replacement — McDonnell & Miller 63-HD head mechanism
Boiler control circuit safety — McDonnell & Miller 7-BM electrical switch with manual reset
Field servicing of flow switches — McDonnell & Miller 310452 cartridge kit
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MCDONNELL Products

3G Electric supplies MCDONNELL replacement hvacr pumps, valves & tubing. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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