What are the quality characteristics of PU hoses and rubberized hoses?

Why are PU flat hoses from Gollmer & Hummel always stable in hose diameter? Why are inside and outside rubberized flat hoses from Gollmer & Hummel better than others?

Product overview

Quality check
GH PU layflat hoses

PU flat hoses are used in various fields: 

As different as these areas are, they place the same demands on hose construction and material: 

  • High abrasion resistance in case of frequent movement or vibration.
  • Sufficient pressure reserves depending on pump capacity and dimensions
  • Resistance to weathering (UV / ozone)
  • Resistance to fertilizers, chemicals, microorganisms
  • Tensile strength
  • Puncture resistance
  • Separation resistance of fabric and PU
Product overview

Quality check
Inside and outside rubberized GH layflat hoses

Inside and outside rubberized flat hoses are mostly used in these fields:  

Again, the requirements for the internally and externally rubberized flat hose are derived from its application:  

  • High abrasion resistance
  • Resistance to oil, gasoline, chemicals
  • Ozone/UV resistance
  • Flexibility
  • Resistance to rotting
Product overview

Inner & outer rubberized multi-purpose heavy duty hose

GH Hilcoflex
Black GH HILCOFLEX as a close up | © GH
Abrasion resistance

Inside and outside rubberized fire hose

GH Progress
Red GH PROGRESS PRO as a close up | © GH
Abrasion resistance
Bending radius

Rugged PU/TPU double fabric hose

GH Drillflex
Abrasion resistance

PU potable water hose according to KTW & DVGW

GH Hilcoflex Aqua
Blue GH HILCOFLEX AQUA as a close up | © GH
Abrasion resistance

TPU DRAg hose for slurry hose systems

GH Hilcoflex PU Drag
Orange GH HILCOFLEX PU DRAG as a close up | © GH
Abrasion resistance
Tensile strength

Hose choice: PU or rubber?
PU and rubber compared

PU is ... 

  • 4 - 5 times more abrasion resistant than rubber.
  • Significantly more resistant than rubber: sharp stones etc. have a much harder time penetrating the outer surface.
  • Tougher than rubber! Mechanical damage to the cover rarely occurs.
  • More layer-separation resistant than rubber, with excellent adhesion values, because liquid PU penetrates the fabric core better.

Laboratory test adhesion - tensile test GH HILCOFLEX PU DRAG - hose diameter 127 mm (according to DIN EN ISO 8033:2006-11)

Adhesion outer cover: 

  • F with minima : 3.79 kN/m
  • F with : 122 N

Adhesion inner core: 

  • F with minima: 3.69 kN/m
  • F with : 114 N
Hose sample after adhesion test | © GH

How do we achieve this quality?
It all comes down to raw materials

Quality starts with the yarn! We pay attention to first-class raw materials such as rubber/TPU-friendly polyester and polyamide (nylon). The yarn is loosely woven in the circular loom. High tensile values of the yarn contribute to the very good separation strength between inner core / textile insert / outer cover and to the flexibility of the finished hose. 


In addition to nitrile rubber, the GH rubber compound consists of up to 20 other ingredients and additives. It is this compound that provides the required UV resistance, chemical resistance and abrasion resistance.

White yarn in production | © GH

Extrusion & fabric centering
Step by step for quality

During extrusion at up to 150 bar pressure, in which the rubber or PU penetrates the loose woven fabric construction, the textile is meticulously centered. The outer layer and inner layer are thus equally thick and resistant at every point.


The textile layer, which is protected in this way in the best possible way, ensures the tensile strength of the hose. In addition, it effortlessly withstands natural abrasion, point loads as well as mechanical damage.


Insight into the hose construction with centered fabric | © GH

Inside and outside rubberized layflat hose
Needling & GH Flatline Vulcanization

When the unvulcanized hose has cooled down after extrusion, the hose passes through a roller system that needles the outer cover. The needling does not pierce the hose or injure the fabric! What looks like a defect at first glance actually ensures the quality of the finished hose, because without this step, the vapors generated in the subsequent vulcanization would escape from the rubber compound in an uncontrolled manner. This could cause parts of the outer cover to detach.


The final step is the special GH Flatline vulcanization

Clamped at both hose ends on a long track, the hoses are filled with hot steam for a certain time: Depending on the hose quality, this takes more than an hour. During the process, the steam pressure increases and is finally pressure tested with water (10 bar).


Only in the GH flatline vulcanization process does rubber develop its familiar material properties such as elasticity, springback and mechanical strength. 


Even after years in use, a Gollmer & Hummel flatline hose rubberized inside and out remains supple and flexible.

Single stage extruded GH HILCOFLEX | © GH

PU layflat hose
GH normalization

The extrusion of PU hoses is followed by a final decisive production step:


In the so-called GH normalization, the hose is optimally prepared for its task. It's as if new shoes didn't have to be broken in first, but fit like a glove immediately and forever. 


The normalized hose convinces with smooth handling and a constant hose diameter from the first to the last use. This makes it easy to re-band a normalized hose if necessary. The normalized PU hose can be reeled up without bulking to save space.

Hose reeled on, providing water for sprinkler system | © GH