512
O
OVENS
300°C For Solvents
Model
PF30-SC PF60-SC PF120-SC PF200-SC
Max. Temp (
O
C)
300
300
300
300
(H)
Chamber Dimensions (mm) (W)
(D)
300
292
320
400
392
420
500
492
520
750
590
520
(H)
Outside Dimensions (mm) (W)
(D)
470
665
470
570
765
570
670
865
670
920
965
670
Chamber Capacity (Liters)
28
66
128
230
Weight (kg)
30
45
60
75
Shelves
Number Supplied
Max. Possible
Max. Dist load/shelf kg
Max load kg
2
3
10
20
2
5
10
30
2
9
10
40
2
15
10
50
Performance
Power Rating at 240V (watts)
1000 1500 2000 2700
Holding Power* at Max. temp. (watts)
350
600
800
1250
Temp. Stability on/off control (
O
C)
±1.0
±1.0
±1.0
±1.0
Temp. Stability PID control (
O
C)
±0.2
±0.2
±0.2
±0.2
Heat up Times* 100
O
C
(Mins) 200
O
C
240V
300
O
C
4.5
12
25
4.5
12
25
4.5
12
25
5.5
14
30
Recovery Times* 100
O
C
(Mins) 200
O
C
Door Open 60sec 300
O
C
240V
1
2.5
4
1
2.5
4
1
2.5
4
1.5
3
5
Air Exchanges vol (l/h) @ 100
O
C
10,000 10,000 10,000 10,000
Air Exchanges (Exchanges/Hour)
360
153
79
44
Most vapor explosions in ovens occur when materials that can absorb large
quantities of solvent are being processed; typical examples being coils &
similar electrical equipment, fibre board & textiles. Every flammable solvent
has a lower & upper flammable limit, & unless the concentration of the
solvent VAPOR is within this range it will not explode. The range widens, for
most solvents, with increasing temp. Precautions must be taken to ensure
that no substantial volume of vapor/air mixture within the range of
flammability can occur in the oven. It is not sufficient to permit an explosive
mixture to form and attempt to obtain safety by preventing foreseeable
means of ignition. The precautions must be directed towards keeping the
concentration of solvent VAPOR down and this is achieved by permitting
only the minimum Quantity of solvent to enter the oven and by ventilating
the oven continuously in use, to dilutes the solvent VAPORs emitted to one
quarter of the lower flammable limit. The “flash-point” of a substance is the
temperature at which it evolves sufficient VAPOR to form an ignitable
mixture with air when tested under standard conditions. Thus, if the flash
point of a liquid is below the temperature of the work room it will give off
VAPOR until (and beyond) the point where the whole room is full of a
flammable mixture, or until all the liquid has evaporated. If the flash point is
is Tittle air movement, with little dilution
of the flammable VAPORs as a result. In
order to improve the temperature
distribution and to obtain an even flow
of air throughout the oven it is normal
to have some form of air recirculation.
A proportion of the VAPOR and fume
laden air should be extracted through a
flue fitted with its own separate exhaust
fan. Reliance on spillage of sufficient
VAPOR and fume laden air through a
rotund draught flue from the
redirection system tends to be
unsatisfactory. An interlock between the
heat source and the exhaust ventilation
is the normal method of ensuring that
sufficient air is Introduced into the oven
for safety.
Explosion Relief & Door Fastening:
Although an oven may be provided with
comprehensive precautions, explosions
can still occur due to failure of
components, inadequate servicing, or
deliberate scotching of safety devices.
The probability of fatal or serious injury
to work people, or serious damage to
the oven, can be reduced substantially
if suitable explosion relief is provided,
coupled with adequate securing of the
doors of the oven to prevent their
becoming missiles in the event of an
explosion. It is recommended that
explosion relief panels are fitted to all
solvent evaporating ovens Irrespective
of chamber volume. These notes cover
the bare essentials of the requirements
for solvent evaporating ovens used in
stovlng and curing processes.
PF30-SC
higher than room temperature, then the liquid will never give off enough VAPOR to form a flammable mixture in the
room. Low flash point solvents are thus intrinsically dangerous. However, the choice of a solvent with a high flash point
will usually make no difference to the safety of the oven used to evaporate it, since the oven almost Inevitably has
a working temperature higher than the flash point. It is still most desirable to choose solvents with the highest possible
flash points to reduce danger at the dipping, spraying and other processes prior to the oven.
Pre-Treatment:
The first step should be to limit as far as possible the amount of solvent entering the oven at each
loading. Particular care is needed with articles which have been dipped in paint or varnish to give a thicker coating
than is usually obtained by spraying. As much drying as possible should be carried out before the articles are added
Into the oven. Where the process permits, it is a good practice, both for safety and economy of heat, to allow the
load to remain for a short time in a semi-enclosure provided with mechanical exhaust ventilation, so that air at room
temperature can remove some of the solvent. This arrangement also has the advantage that dripping in the oven is
reduced, whereby the accumulation of paint and varnish residues in the oven became less of a problem.
Ventilation:
Reliance on natural convection currents up the chimney is not normally an acceptable method of
introducing sufficient fresh air into the oven to prevent a solvent/air explosion mixture forming. The oven should be
fitted with mechanical exhaust ventilation. It is important that the exhaust draught should be applied at points in the
oven where the rate of evaporation is a maximum, and that there are no dead spots in the oven space where there
PF-SC Series, 300
O
C Ovens For Solvents
