Intro For pump and pressure-screen operators seeking a dependable Burgmann LP-D replacement, FBU Sealing Technology (FBU) offers the 2750 double mechanical seal engineered for heavy-duty equipment. This article compares the Burgmann LP-D and FBU 2750 side-by-side, highlights compatibility with Sulzer A (Ahlstar) pumps and common pressure-screen brands, and explains why the 2750 is a practical alternative for demanding pulp, paper and process applications.

Intended use

• Burgmann LP-D: Integrated, dual, semi-cartridge seal optimized for Sulzer A pumps and non-flow use in pressure-screen applications.

• FBU 2750: Double-balanced, double-acting seal designed for pressure screens, pumps and heavy-process equipment handling solids and abrasive media.

Pressure & temperature capability

• LP-D: p1 up to 25 bar (p3 <12 bar); temp −20 °C to +140 °C (up to 180 °C with Kalrez®).

• 2750: Seal chamber ≤ 20 bar; buffer water ≤ 15 bar; temp −20 °C to +180 °C. 

Velocity & stock content

• LP-D: Sliding velocity up to 20 m/s (non-flow <10 m/s); stock content <8%.

• 2750: Sliding velocity ≤ 30 m/s; suitable for liquids with solids and impurities (common in screens and pulpers).

Design highlights 

• LP-D: Dual, pressure-balanced; internal barrier fluid circulation; static springs both sides; no dynamic shaft O-ring; rugged, shrink-fitted faces; large radial clearance for shaft protection.

• 2750: Double-balanced with independent multi-spring structures for stable loading; rugged heavy-duty construction; diversion pipe directing buffer fluid to the faces; low maintenance, easy installation; recommended with GLD (Plan 54).

Materials & sealing elements

• LP-D: Silicon carbide / carbon faces; FKM, EPDM, FFKM secondary seals; CrNiMo steel and high-grade alloys for metal parts.

• 2750: Available in 316SS, Duplex, Titanium and other alloys; face and secondary material options customizable to match media and temperature requirements.

Compatibility & typical equipment

• LP-D: Specifically integrated for Sulzer Ahlstar A (MS11) pumps and pressure screens where non-flow operation and quench/buffer arrangements are used.

• 2750: Designed for pressure screens and heavy equipment from Andritz, Ahlstrom, Valmet, Metso Paper, Voith, Toscotec and similar OEMs; sizes typically 50–200 mm, making it a practical match for many Sulzer A pump installations used in the paper industry.

Why choose FBU 2750 as an LP-D alternative

• Comparable functional coverage: The 2750 matches or exceeds LP-D capabilities for temperature range (to 180 °C), sliding velocity, and duty with solids-containing media typical of pressure screens.

• Robust for heavy-duty use: Engineered for equipment that processes abrasive and particulate-laden liquids — common in pulp, paper, lithium, CCUS and alternative-fuel operations.

• Flexible materials & piping plans: Multiple alloy options and compatibility with common piping plans (Plan 52, 53 variants, 54) facilitate integration into existing barrier/buffer systems.

• Minimized downtime and maintenance: Rugged design, direct buffer diversion to the friction pair, and straightforward installation reduce service frequency and parts inventory.

Installation & maintenance considerations

FBU 2750 is supplied to suit common chamber sizes (50–200 mm). Confirm shaft dimensions, chamber clearances, piping-plan requirements (e.g., Plan 54 recommended for seal water control), and barrier-fluid conditions before ordering.

For retrofit: measure existing LP-D assembly, note face materials and secondary elastomers, and determine whether quench/buffer or single/double configuration is required. FBU can supply matching materials and advice for interchange to minimize rework.

Technical fit checklist (quick)

• Shaft diameter and seat dimensions compatible

• Required pressure and temperature within 2750 ratings

• Barrier/buffer plan (Plan 52/53/54) available or adaptable

• Media abrasiveness and solids loading considered for material selection

• Ordering & support FBU provides technical support to confirm fitments and material selections for retrofitting Burgmann LP-D seals with the 2750. Contact our engineering team with pump model, chamber dimensions, operating pressures, temperatures, media description, and any piping-plan in use.

FAQ 

1: Can the FBU 2750 be used as a direct drop-in replacement for Burgmann LP-D? 

In many cases yes, but compatibility depends on chamber dimensions and shaft/seat interfaces. Provide measurements and operating conditions to confirm a direct retrofit or recommend minor adaptions.

2: Is the 2750 suitable for non-flow (standstill) operation? 

The 2750 is engineered for heavy-duty and solids-bearing services. For non-flow or quench-specific operating envelopes, confirm barrier fluid and pressure arrangements; 2750 supports common piping plans including Plan 54.

3: What materials do you recommend for abrasive or corrosive liquids? 

Options include Duplex or corrosion-resistant alloys (Titanium), and appropriate face/secondary combinations. We’ll propose materials based on your media analysis.

4: Which piping plan should I use? 

For screen sealing we recommend GLD/Plan 54 for active seal water control; Plans 52/53 variants are also supported depending on application specifics.

5: How does maintenance and spare-part stocking compare?

The 2750 is designed to minimize wear parts and simplify maintenance. FBU can provide recommended spare kits aligned to your operating profile.

 

Next steps Send us your pump model (e.g., Sulzer A/Ahlstar), shaft and chamber dimensions, operating pressures/temperatures, and a brief description of the media. FBU engineering will verify fitment and provide a quote and retrofit recommendation.

For assistance or to request a compatibility check, contact FBU Sealing Technology with your application details.