A Symbol for sliding face. |
A Listed in first or second position of the Material Code according to DIN 24 960, A is the code letter for carbon graphite, metal impregnated (metalimpregnated carbons). In third position A stands for asbestos, impregnated. |
AFNOR Abbreviation for Association Française de Normalisation (French standards institute). |
AH Hydraulically loaded area. |
AISI Abbreviation for American Iron and Steel Institute, one of the American organizations which among other things draw up specifications. A comparison of the most common AISI material numbers (including analysis) with the corresponding material numbers according to DIN 17 007 can be found e.g. in the Steel Code. |
AM-350 Designation for a chromium-nickel-molybdenum steel exceptional for its high strength, good resistance to corrosion and good spring properties. It is used e.g. to manufacture metallic bellows. Analysis: 16-17% Cr, 4.0-5.0% Ni, 2.5-3.25% Mo, 0.5-1.25% Mn, 0.07-0.13% N, 0.3-0.5 % Si, 0.07-0.13 % C. |
ANSI Abbreviation for American National Standards Institute. ANSI standards find application mainly in plant engineering, including outside the U.S.A., e.g. ANSI B 73.1: Specification for Horizontal, End Suction Centrifugal Pumps for Chemical Process. |
API Abbreviation for American Petroleum Institute. Published API standards are based on the pooled knowledge and experience of manufacturers and users of machinery for mineral oil production and processing. API standards are described by API itself as an aid for machine selection and for manufacturer/user communication. On the practical level, however, API standards are mostly treated as binding standards. |
API 610 Commonly used abbreviation for API Standard 610 published by the American Petroleum Institute: Centrifugal Pumps for General Refinery Services. In Appendix D and E to API 610 descriptions are given of mechanical seal configurations, circulation systems (circulation of a separate medium, circulation of the pumped medium), cooling systems and a coding system for seals. DIN ISO 5199 and VDMA 24297 are identical with the meaning of API 610 in many decisive points. |
API 614 Cf. API and API 610. API Standard 614: Lubrication, Shaft-Sealing, and Control-Oil Systems for Special-Purpose Applications, contains guidelines for selecting and describing the basic types of oil supply systems for the bearing and shaft seal (mostly double mechanical seals) of large machines. The most frequently used buffer fluid unit in accordance with API 614 consists of a circulation pump, which sucks the buffer oil out of the pressureless storage vessel, raises it to the required level of pressure and conveys it via a cooler, the mechanical seal and a throttle mechanism back into the storage vessel. As consumers of a relatively large amount of energy these units are being replaced increasingly by refill units, which compensate only the loss of buffer oil and pressure caused by leakage. A further advantage of these refill units - not yet covered by API 614 - in addition to their substantially lower energy requirement is that they enable all other common buffer media to be used in place of oil. |
ASME Abbreviation for American Society of Mechanical Engineers. Familiar on account of the ASME Boiler and Pressure Vessel Code, called ASME Code for short; an extensive set of rules for the design, calculation, material selection, manufacture and testing of pressure vessels. The ASME Code is often taken as basis internationally for the construction of components used in power stations and nuclear power stations. |
ASTM Abbreviation for American Society for Testing and Materials. |
ASTM D 1418-85: Practice for Rubber and Rubber Lattices, Nomenclature. The symbols for elastomers specified in this standard are in international use. (Table in materials for secondary seals). |
B Listed in first or second position of the Material Code according to according to DIN 24 960, B is the code letter for carbon graphite, resin-impregnated (resin impregnated carbons). In third position B stands for butyl rubber. |
b Symbol for spring constant. |
C Listed in first or second position of the Material Code according to DIN 24 960, C is the code letter for miscellaneous carbons. |
D Listed in first or second position of the Material Code according to DIN 24 960, D is the code letter for C-steel (hardened). In fourth of fifth place D stands for C-steel. |
d Symbol for the diameter of wire in a spring. |
dA Symbol for part of an area. |
da Symbol for the outer diameter of a bellows. |
dE Symbol for the diameter of the fluid inlet at the sliding face. |
dFn Symbol for the normal components of an element of force. |
dFt Symbol for the tangential components of an element of force. |
dH Symbol for the hydraulic diameter. |
di Symbol for the inner diameter of a bellows. |
DIN Abbreviation for Deutsches Institut für Normung e.V., which publishes German standards (DIN Normen) under the DIN mark. Some of the DIN standards affecting the design, production and operation of mechanical seals in pumps and agitators. |
dm Symbol for the mean diameter of a seal face. |
e Symbol for the axial length of the rotating part of a seal. |
E Listed in first or second position of the Material Code according to DIN 24 960, E is the code letter for Cr-steel (chromium steel). In third position E stands for EP rubber (ethylene-propylene diene rubber). In fourth or fifth place E stands for Cr-steel. |
f Symbol for the coefficient of friction. |
F Symbol for spring force. |
FD Symbol for sealing force. |
FEP fluorinated ethylene-propylene rubber. |
FF Symbol for absolute spring force. |
FH Symbol for hydraulic loading force. |
FR Symbol for frictional force. |
FSchl Symbol for closing force. |
FSp Symbol for the force of the gap pressure (force in the sealing gap). |
g Symbol for acceleration due to gravity. |
G Symbol for shear modulus. |
h Symbol for height of gap. |
H Symbol for delivery head. |
IMO Abbreviation for the International Maritime Organization, which took over from IMCO. One of its functions is to draw up transport regulations for conveying dangerous goods on sea (IMDG Code). |
ISO Abbreviation for the International Organization for Standardization. |
ISO 3069 "End suction centrifugal pumps - Dimensions of cavities for mechanical seals and for soft packing." It covers the establishment of shaft diameters and of relative stuffing box compartment diameters. These dimensions are identical with the corresponding dimensions in DIN 24 960. |
ISO 5199 DIN ISO 5199 |
k Symbol for load factor. |
K Listed in first or second position of the Material Code according to DIN 24 960, K is the code letter for chronium-nickel-molybdenum steel, stellitized (stellite) |
l Symbol for tube length. |
L Listed in first or second position of the Material Code according to DIN 24 960 L is the code letter for stellite. |
LK Symbol for the critical spring length. |
LNG Abbreviation for liquefied natural gas. Cf. liquefied petroleum gases, cryogenic seals. |
Lo Symbol for spring length. |
LPG Abbreviation for liquefied petroleum gas (gasoline). Cf. liquefied petroleum gases, cryogenic seals. |
m Symbol for mass. |
M Listed in first or second position of the Material Code according to DIN 24 960, M is the code letter for high-nickel alloy. In third position M stands for PTFE-covered (encapsulated O-rings). In fourth and fifth place M stands for high-nickel alloy. |
n Symbol for (rotational) speed (rpm). |
N Listed in first or second position of the Material Code according to DIN 24 960, N is the code letter for bronze. In third place N stands for chloroprene rubber. In fourth and fifth position N is the code letter for bronze. |
NACE Abbreviation for the National Association of Corrosion Engineers, 1440 South Creek Dr., Houston, Texas 77084. NACE is known among other things as the publisher of a reference work listing the resistance characteristics of materials in relation to a large number of aggressive media: Corrosion Data Survey, Metals section, Nonmetals. |
NF E 29-991 French standard identical in content with DIN 24960 (June 1980). |
NPSH NPSH -net positive suction head. DIN 24 260 (September 1984) defines this unit as follows: "Net energy level (= absolute energy level less the vaporization pressure level) in the inlet cross section of the pump. The vaporization pressure at the temperature prevailing in the inlet cross section of the pump must be taken as the vaporization pressure level." A distinction is drawn between the "Actual NPSH (NPSHA): The NPSH from the system side at a given flow and with the respective pumped liquid, and the "Required NPSH (NPSHR): The smallest NPSH value at which a specific cavitation criterion is fulfilled, e.g. delivery head reduction, noise, oscillation, steam bubble proliferation, cavitation wear." Operation without cavitation is conditional therefore on the actual NPSH on the system side being greater than the required NPSH on the pump side. A little known phenomenon (and one rarely disclosed in the characteristic curves of many pumps) is the sharp rise in the NPSHR at very low delivery rates or when the value drops below the minimum flow Q min; such a rise can lead to cavitation-induced damage to the pump and the mechanical seal (cavitation). Delivery/NPSHR
curve
|
p Symbol for pressure. |
P Listed in first or second position of the Material Code according to DIN 24 960, P is the code letter for grey cast iron. In third position P stands for nitrite rubber (acrylonitrile butadiene rubber). D p stands for the differential pressure to be sealed. |
p(r) Symbol for the pressure characteristic in the sealing gap. |
p1 Symbol for operating pressure. |
p2 Symbol for ambient pressure. |
p3 Symbol for buffer pressure. |
pA Symbol for sealing pressure. |
pabs Symbol for absolute pressure. |
pamb Symbol for atmospheric pressure. |
PCTFE PCTFE is the abbreviation for polychlorotrifluoroethylene specified in DIN 7728, Part 1 (April 1978). |
pe Symbol for atmospheric pressure differential. |
pE Symbol for discharge pressure. |
Pf Symbol for specific spring force. |
pf Symbol for spring force relative to the sliding face. |
pF Symbol for specific spring loading. |
Pg Symbol for sliding pressure. |
ps Symbol for intake pressure. |
Pt 100 resistance thermometer. |
PTB Abbreviation for Physikalisch-Technische Bundesanstalt, Braunschweig, Federal Republic of Germany. The institute conducts the necessary tests on and issues certificates for equipment intended for use in potentially explosive areas. |
PTFE and (PTFE... reinforced) polytetrafluoroethylene. |
Pv Symbol for pressure loss |
Q Symbol for delivery rate |
QA Commonly used abbreviation for quality assurance. |
R Symbol for spring rate. |
Ra Symbol for the arithmetic mean roughness index. |
rg Symbol for face radius. |
Rz Symbol for the average peak-to-valley height. |
s Symbol for spring excursion. |
S Symbol for gap factor. |
SAE Abbreviation for Society of Automotive Engineers, New York, a standardization institute in the motor vehicle field. One of its activities is to classify lubricating oils. SAE viscosity classes provide information about the flow characteristics demanded for oils, but they do not specify their composition or quality. |
SiC Chemical formula and customary abbreviation for silicon carbide. |
SIS Abbreviation for Standardiseringskommision i Sverige, renamed Svensk Standard (SS for short) in 1978. Such material designations as e. g. SIS 2343, which are also familiar - especially in the pulp and paper industry - outside Sweden, now read e.g. SS 2343. |
SS Abbreviation for stainless steel and for Svensk Standard (SIS). |
S-SiC Common mnemonic for pressureless sintered silicon carbide (sintered silicon carbide). |
t Symbol for temperature. |
T Listed in first or second position of the Material Code according to DIN 24 960, T is the code letter for miscellaneous metal. In third place T stands for PTFE (polytetrafluoroethylene). In fourth and fifth position T stands for miscellaneous materials. |
t3 Symbol for temperature of buffer fluid. |
TRB Abbreviation for Technische Regeln für Druckbehälter (Technical Rules for Pressure Vessels), a code of regulations published by the central office for accident prevention and industrial medicine of the Federation of German Commercial Employer's Insurance Associations. It contains the generally approved rules of engineering established by the pressure vessel special committee for the materials, fabrication, calculation, equipment installation, testing and operation of pressure vessels. |
TRD Abbreviation for Technische Regeln für Dampfkessel (Technical Rules for Steam Boilers), a code of regulations drawn up by the German Steam Boiler Committee. It lists the current safety requirements for the materials, fabrication, calculation, equipment, installation, testing and operation of steam boilers. |
TTE A BURGMANN designation for an O-ring whose core of ethylene propylene diene rubber is encapsulated in two PTFE coatings for greater chemical and thermal resistance. |
TTN A BURGMANN designation for an O-ring whose core of chlorobutadiene rubber is encapsulated in two PTFE coatings for greater chemical and thermal resistance. |
TTS A BURGMANN designation for an O-ring whose core of silicon rubber is encapsulated in two PTFE coatings for greater chemical and thermal resistance. |
TTV A BURGMANN designation for an O-ring whose core of fluorocarbon rubber is encapsulated in two PTFE coatings for greater chemical and thermal resistance. |
TTV/T A BURGMANN designation for a secondary seal combination consisting of a TTV-type O-ring as a dynamically loaded secondary seal between the seal face and shaft (sleeve), and a solid-PTFE O-ring as a static seal between the stationary seat and housing (cover). |
TÜA Abbreviation for Technisches Überwachungsamt (Technical Inspectorate Office). Its duties and functions are identical with those of the TÜV. In some Federal German states (e.g. Hesse), the state-registered TÜV was liquidated and reinstalled as a governmental testing agency. In reflection of the change of status from "Verein" (association) to "Amt" (office), the official name of the inspectorate was altered accordingly. |
TÜV Abbreviation for Technischer Überwachungsverein, a state-registered testing agency independent of manufacturers and operators. Among other things, it conducts statutory testing and monitoring activities independently of manufacturers and operators. TÜV associations fall under the jurisdiction of the respective federal states. |
U Listed in first or second position of the Material Code according to DIN 24 960, U is the code letter for metal carbides. In third position U stands for combination of materials for secondary seals (p. ex. TTV/T). |
V Symbol for volume. |
VbF German abbreviation for the national regulation concerning the construction and operation of plants to store, transfer and convey flammable liquids on land. |
Vo Symbol for nominal volume. |
W Listed in first or second position of the Material Code according to DIN 24 960, W is the code letter for Cr oxide (chromium oxide). |
w Symbol for flow velocity. |
X Listed in first or second position of the Material Code according to DIN 24 960, X is the code letter for miscellaneous metallic oxides. In third place X stands for miscellaneous elastomers. |
Y Listed in first or second position of the Material Code according to DIN 24 960, Y is the code letter for PTFE, reinforced (Polytetrafluorethylene). In third place Y stands for miscellaneous non-elastomers. |
Z Listed in first or second position of the Material Code according to DIN 24 960, Z is the code letter for miscellaneous plastics. |
