Chapter 1: Machine And Pumped Fluid Specifications; Envisioned Duration; Technical Description Of The Machine - OMAC B Series Operation And Maintenance Manual

Table of Contents

Rev.4 del 01/2011 O.M.A.C. s.r.l.

1.1 Envisioned duration

Given the quality level of the materials and construction technologies used, if you strictly follow the instructions in this OMM (paying particular attention

to chapters 3, 4 and 5, relating, respectively, to the installation, use and maintenance of the LDPU), the expected duration of such subject matter is

estimated to be 12 months from date of installation.

Please note that, during its expected life-span, the LDPU must not be assembled and/or disassembled by unauthorised personnel and furthermore the

instructions contained in this UMM must be followed scrupulously.

1.2 Technical description of the machine

Below there is a brief description of the LDPU, as well as a functional illustrational of the B series LDPU, in order to more easily identify the main con-

struction details, mentioned in the description of use and maintenance of this document.

The LDPU is made up of 3 macro-components:

1) control unit (gear motor, speed controller, hydraulic motor,

electric panel, etc.);

2) mechanical transmission device (ﬂ exible transmission coupling);

3) B Series LDPU;

The B Series LDPU, identiﬁ ed with number 3)

is made up as follows:

M = Drive shaft

A = Rotorcase cover

N = Fixed gear

B = Lock nut

O = Oil level cap

C = Rotor

P = Adjustable gear

D = Seal

R = Driven shaft

E = Balancing ring

S = Bearing housing

F = Bearing retainer ring

T = Foot

G = Front Bearing

U = Rotorcase

H = Rear bearing

V = Seal protection

K = Oil vent cap

L = Rear cover

1.2.1 Operation principle of the B Series

LDPU.

The LDPU, whose functional element is the B Series

lobe positive displacement pump, is equipped with a

control unit that, depending on the version, can be ﬁ tted

with a gear motor, an electric motor, a pneumatic motor

or a hydraulic motor, with or without electric panel.

The capacity adjustment is achieved by increasing or

decreasing the number of revolutions of the B series

lobe positive displacement pump, intervening directly

on the revolutions output of the motor or acting on the

actuators on the control panel (inverter), if ﬁ tted.

The LDPU is reversible: full performance can be achieved in both rotation directions of the pump rotors (section 1.3.5 of chapter 1 lists the types of rotors

used).

The pumping action of the B series lobe displacement pump is achieved thanks to the counter-rotation of two rotors (letter "C" indicated in the ﬁ gure in

section 1.2, indicating one of the two rotors), housed inside the pumping chamber (letter "U" indicated in the ﬁ gure in section 1.2 or see ﬁ gure below). The

rotors are assembled on rotating shafts supported by bearings (letters "G" and "H" shown in the ﬁ gure in section 1.2), which are housed in the external

gearbox (letter "S" shown in the ﬁ gure in section 1.2). Via a couple of sprocket wheels (letters "N" and "P" indicated in the ﬁ gure in section 1.2) one

transfers motion from a drive shaft (letter "M" indicated in the ﬁ gure in section 1.2) to a driven shaft (letter "R" indicated in the ﬁ gure in section 1.2). The

synchronism of the rotors is such that they rotate without coming into contact with each other: in these conditions "the rotors are in time".

When the lobes of the rotors move away from each other, the volume between them increases, creating a decrease in pressure near the suction outlet:

this enables a certain volume of ﬂ uid to enter (value of ﬂ uid transported identiﬁ ed in the table in section 1.3.1, in the "theoretical capacity" column,

depending on the pump model size) into the rotorcase. The ﬂ uid is transported along the internal of the pumping chamber, from the suction inlet to the

discharge outlet of the rotorcase.

When the volume of ﬂ uid, trapped between the lobes and the external perimeter of the pumping chamber, reaches in proximity of the discharge outlet,

the counter-rotation of the two rotors creates a sudden decrease of available volume and a consequent increase in pressure that pushes the ﬂ uid out of

the rotorcase, by channelling it into the plant where the LDPU is installed.